diff --git a/Koha/Exceptions/Patron/Relationship.pm b/Koha/Exceptions/Patron/Relationship.pm
index abc5baa2c0..768d5a1b0f 100644
--- a/Koha/Exceptions/Patron/Relationship.pm
+++ b/Koha/Exceptions/Patron/Relationship.pm
@@ -32,7 +32,10 @@ use Exception::Class (
     'Koha::Exceptions::Patron::Relationship::InvalidRelationship' => {
         isa         => 'Koha::Exceptions::Patron::Relationship',
         description => 'The specified relationship is invalid',
-        fields      => [ 'relationship', 'no_relationship', 'invalid_guarantor', 'child_guarantor' ]
+        fields      => [
+            'relationship', 'no_relationship', 'invalid_guarantor', 'child_guarantor',
+            'guarantor_cant_have_guarantors', 'guarantor'
+        ],
     },
     'Koha::Exceptions::Patron::Relationship::NoGuarantor' => {
         isa         => 'Koha::Exceptions::Patron::Relationship',
diff --git a/Koha/Patron.pm b/Koha/Patron.pm
index 3740132295..7b8b69315b 100644
--- a/Koha/Patron.pm
+++ b/Koha/Patron.pm
@@ -2802,34 +2802,59 @@ sub _anonymize_column {
     $self->$col($val);
 }
 
-=head3 validate_guarantor
+=head3 can_be_guaranteed_by
 
-    Koha::Patron->validate_guarantor(\@guarantors, $contactname, $category );
+    $patron->can_be_guaranteed_by( [
+        $guarantor1,
+        $guarantor2,
+        ...
+    ] );
 
-    Validates guarantor patron.
+    Given an array of guarantors, checks if they can be guarantors for this patron.
+
+    Throws Koha::Exceptions::Patron::Relationship::InvalidRelationship if a proposed
+        guarantor cannot be a guarantor for this patron.
+
+    $patron->can_be_guaranteed_by();
+
+    Given no guarantors, checks if this patron must be guaranteed by someone. Read
+    "can be guaranteed by nobody".
+
+    Throws Koha::Exceptions::Patron::Relationship::NoGuarantor if this patron must
+        have a guarantor.
 
 =cut
 
-sub validate_guarantor {
-    my ( $self, $guarantors, $contactname, $category ) = @_;
+sub can_be_guaranteed_by {
+    my ( $self, $guarantors ) = @_;
 
-    my $valid_guarantor = @$guarantors ? @$guarantors : $contactname;
+    my $category = $self->category;
 
     if (    C4::Context->preference('ChildNeedsGuarantor')
         and ( $category->category_type eq 'C' or $category->can_be_guarantee )
-        and !$valid_guarantor )
+        and scalar @$guarantors == 0 )
     {
         Koha::Exceptions::Patron::Relationship::NoGuarantor->throw();
     }
 
+    if ( $self->is_guarantor && scalar @$guarantors > 0 ) {
+        Koha::Exceptions::Patron::Relationship::InvalidRelationship->throw( guarantor_cant_have_guarantors => 1 );
+    }
+
     foreach my $guarantor (@$guarantors) {
+        next if ref($guarantor) ne 'Koha::Patron';
+
         if ( $guarantor->is_guarantee ) {
-            Koha::Exceptions::Patron::Relationship::InvalidRelationship->throw( invalid_guarantor => 1 );
+            Koha::Exceptions::Patron::Relationship::InvalidRelationship->throw(
+                invalid_guarantor => 1,
+                guarantor         => $guarantor,
+            );
         } elsif ( $guarantor->is_child ) {
             Koha::Exceptions::Patron::Relationship::InvalidRelationship->throw( child_guarantor => 1 );
         }
     }
 
+    return 1;
 }
 
 =head3 add_guarantor
diff --git a/koha-tmpl/intranet-tmpl/prog/en/modules/members/memberentrygen.tt b/koha-tmpl/intranet-tmpl/prog/en/modules/members/memberentrygen.tt
index 312fe4b1bd..9e8bf04c0b 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/modules/members/memberentrygen.tt
+++ b/koha-tmpl/intranet-tmpl/prog/en/modules/members/memberentrygen.tt
@@ -195,10 +195,16 @@
                                     <li id="ERROR_child_is_guarantor">Child patron cannot be a guarantor.</li>
                                 [% END %]
                                 [% IF ( ERROR_guarantor_is_guarantee ) %]
-                                    <li id="ERROR_guarantor_is_guarantee">A guarantee cannot be a guarantor.</li>
+                                    <li id="ERROR_guarantor_is_guarantee">
+                                        Cannot add a guarantor. The proposed guarantor
+                                        <a href="/cgi-bin/koha/members/moremember.pl?borrowernumber=[% guarantor_is_guarantee.borrowernumber | uri %]" target="blank">
+                                            [% guarantor_is_guarantee.firstname | html %] [% guarantor_is_guarantee.surname | html %] ([% guarantor_is_guarantee.cardnumber | html %])
+                                        </a>
+                                        is a guarantee of someone else, and guarantees cannot be guarantors.</li
+                                    >
                                 [% END %]
-                                [% IF ( ERROR_guarantee_is_guarantor ) %]
-                                    <li id="ERROR_guarantee_is_guarantor">A guarantor cannot be a guarantee.</li>
+                                [% IF ( ERROR_guarantor_cant_have_guarantors ) %]
+                                    <li id="ERROR_guarantor_cant_have_guarantors">Cannot add a guarantor. This patron is already a guarantor, and guarantors cannot have guarantors.</li>
                                 [% END %]
                                 [% IF ( ERROR_cannot_delete_guarantor ) %]
                                     <li id="ERROR_cannot_delete_guarantor">Cannot delete guarantor(s). A child patron needs a guarantor.</li>
diff --git a/members/memberentry.pl b/members/memberentry.pl
index 2ee52ea66a..ec02bec7d1 100755
--- a/members/memberentry.pl
+++ b/members/memberentry.pl
@@ -23,7 +23,8 @@ use Modern::Perl;
 use Try::Tiny;
 
 # external modules
-use CGI qw ( -utf8 );
+use CGI          qw ( -utf8 );
+use Scalar::Util qw( blessed );
 
 # internal modules
 use C4::Auth qw( get_template_and_user haspermission );
@@ -52,7 +53,8 @@ use Koha::SMS::Providers;
 my $input = CGI->new;
 my %data;
 
-my $dbh = C4::Context->dbh;
+my $dbh    = C4::Context->dbh;
+my $logger = Koha::Logger->get( { interface => 'intranet ' } );
 
 my ( $template, $loggedinuser, $cookie ) = get_template_and_user(
     {
@@ -273,33 +275,61 @@ if (@delete_guarantor) {
     if ( C4::Context->preference('ChildNeedsGuarantor') && $will_remove_last ) {
         push @errors, 'ERROR_cannot_delete_guarantor';
     } else {
+        my @deleted_guarantors;
         foreach my $id (@delete_guarantor) {
             my $r = Koha::Patron::Relationships->find($id);
-            $r->delete() if $r;
+            if ($r) {
+                $r->delete();
+                push @deleted_guarantors, $id;
+            }
+        }
+        foreach my $deleted_guarantor_id (@deleted_guarantors) {
+            @guarantors = grep { ref($_) eq 'Koha::Patron' && $_->id ne $deleted_guarantor_id } @guarantors;
         }
     }
 }
 
 #Check if guarantor requirements are met
-if ( ( $op eq 'cud-save' || $op eq 'cud-insert' ) ) {
-    unless ( $patron && $patron->is_guarantor ) {
-        try {
-            Koha::Patron->validate_guarantor( \@guarantors, $newdata{'contactname'}, $category );
-        } catch {
-            if ( ref($_) eq "Koha::Exceptions::Patron::Relationship::NoGuarantor" ) {
-                push @errors, "ERROR_child_no_guarantor";
-            } elsif ( ref($_) eq "Koha::Exceptions::Patron::Relationship::InvalidRelationship" ) {
-                if ( $_->full_message eq "Guarantee patron cannot be a guarantor." ) {
-                    push @errors, "ERROR_guarantor_is_guarantee";
-                } elsif ( $_->full_message eq "Child patron cannot be a guarantor." ) {
-                    push @errors, "ERROR_child_is_guarantor";
-                }
+my $guarantors_to_be_validated =
+    @guarantors ? \@guarantors : $newdata{'contactname'} ? [ $newdata{'contactname'} ] : [];
+if ( ( $op eq 'cud-save' || $op eq 'cud-insert' ) && $guarantors_to_be_validated ) {
+    try {
+        if ($patron) {
+            if ( $patron->categorycode eq $categorycode ) {
+                $patron->can_be_guaranteed_by($guarantors_to_be_validated);
+            } else {
+
+                # If $patron's categorycode is about to change, check guarantor requirements against
+                # the new category but keep the original $patron object intact
+                # (this clone()s the $patron)
+                ( bless {%$patron}, ref $patron )->categorycode($categorycode)
+                    ->can_be_guaranteed_by($guarantors_to_be_validated);
             }
-            return;
-        };
-    } else {
-        push @errors, "ERROR_guarantee_is_guarantor";
-    }
+        } else {
+            Koha::Patron->new( { categorycode => $categorycode } )->can_be_guaranteed_by($guarantors_to_be_validated);
+        }
+    } catch {
+        unless ( blessed($_) ) {
+            $logger->error($_);
+        } else {
+            if ( $_->isa("Koha::Exceptions::Patron::Relationship::NoGuarantor") ) {
+                push @errors, "ERROR_child_no_guarantor";
+            } elsif ( $_->isa("Koha::Exceptions::Patron::Relationship::InvalidRelationship") ) {
+                if ( $_->invalid_guarantor ) {
+                    push @errors, "ERROR_guarantor_is_guarantee";
+                    $template->param( guarantor_is_guarantee => $_->guarantor );
+                } elsif ( $_->child_guarantor ) {
+                    push @errors, "ERROR_child_is_guarantor";
+                } elsif ( $_->guarantor_cant_have_guarantors ) {
+                    push @errors, "ERROR_guarantor_cant_have_guarantors";
+                }
+            } else {
+                $logger->error( $_->error );
+                $_->rethrow;
+            }
+        }
+        return;
+    };
 }
 
 my @valid_relationships = split( /\|/, C4::Context->preference('borrowerRelationship'), -1 );
diff --git a/t/db_dependent/Koha/Patron.t b/t/db_dependent/Koha/Patron.t
index 35e1b4d8ff..44802ce4ba 100755
--- a/t/db_dependent/Koha/Patron.t
+++ b/t/db_dependent/Koha/Patron.t
@@ -2624,7 +2624,7 @@ subtest 'get_lists_with_patron() tests' => sub {
     $schema->storage->txn_rollback;
 };
 
-subtest 'validate_guarantor() tests' => sub {
+subtest 'can_be_guaranteed_by() tests' => sub {
 
     plan tests => 5;
 
@@ -2659,6 +2659,12 @@ subtest 'validate_guarantor() tests' => sub {
             value => { categorycode => $guarantor_category->{categorycode} }
         }
     );
+    my $patron2 = $builder->build_object(
+        {
+            class => 'Koha::Patrons',
+            value => { categorycode => $guarantor_category->{categorycode} }
+        }
+    );
 
     my @guarantors;
     my $contactname = "";
@@ -2666,28 +2672,30 @@ subtest 'validate_guarantor() tests' => sub {
 
     t::lib::Mocks::mock_preference( 'ChildNeedsGuarantor', 0 );
 
-    lives_ok { $child->validate_guarantor( \@guarantors, $contactname, $category ); }
+    lives_ok { $child->can_be_guaranteed_by( \@guarantors ); }
     'Validation passes when ChildNeedsGuarantor syspref is disabled';
 
     t::lib::Mocks::mock_preference( 'ChildNeedsGuarantor', 1 );
 
-    throws_ok { $child->validate_guarantor( \@guarantors, $contactname, $category ); }
+    throws_ok { $child->can_be_guaranteed_by( \@guarantors ); }
     'Koha::Exceptions::Patron::Relationship::NoGuarantor',
         'Exception thrown when guarantor is required but not provided.';
 
     @guarantors = ( $patron, $child2 );
-    throws_ok { $child->validate_guarantor( \@guarantors, $contactname, $category ); }
+    throws_ok { $child->can_be_guaranteed_by( \@guarantors ); }
     'Koha::Exceptions::Patron::Relationship::InvalidRelationship',
         'Exception thrown when child patron is added as guarantor.';
 
-    @guarantors = ($patron);
-    lives_ok { $child->validate_guarantor( \@guarantors, undef, $category ); }
-    'Validation passes when valid guarantors are passed in array';
+    t::lib::Mocks::mock_preference( 'borrowerRelationship', 'parent' );
+    $child2->add_guarantor( { guarantor_id => $patron->id, relationship => 'parent' } );
+    @guarantors = ($patron2);
+    throws_ok { $patron->can_be_guaranteed_by( \@guarantors ); }
+    'Koha::Exceptions::Patron::Relationship::InvalidRelationship',
+        'Exception thrown when trying to add a guarantor to a guarantor.';
 
-    @guarantors  = ();
-    $contactname = "Guarantor";
-    lives_ok { $child->validate_guarantor( \@guarantors, $contactname, $category ); }
-    'Validation passes when guarantor contanct name is passed';
+    @guarantors = ($patron);
+    lives_ok { $child->can_be_guaranteed_by( \@guarantors ); }
+    'Validation passes when valid guarantors are passed in array';
 
     $schema->storage->txn_rollback;
 };