diff --git a/src/collections/blocks/ImageCards.ts b/src/collections/blocks/ImageCards.ts
index 706f8bb..6da28b6 100644
--- a/src/collections/blocks/ImageCards.ts
+++ b/src/collections/blocks/ImageCards.ts
@@ -36,6 +36,14 @@ export const ImageCardsBlock: Block = {
           admin: {
             condition: (_, siblingData) => !siblingData?.customLink,
           },
+          hooks: {
+            beforeChange: [
+              // Write null instead of undefined so the Postgres adapter removes stale
+              // _rels rows left behind by block reordering, otherwise they resurface
+              // as this card's link: https://github.com/payloadcms/payload/issues/16647
+              ({ value, siblingData }) => (siblingData?.customLink ? null : (value ?? null)),
+            ],
+          },
         },
         {
           name: 'customLink',
@@ -43,9 +51,8 @@ export const ImageCardsBlock: Block = {
           type: 'text',
           required: false,
           admin: {
-            condition: (_, siblingData) => !siblingData?.link,
             description:
-              'Alternative zu "Verknüpfung". Nur eins von beiden kann gesetzt werden.',
+              'Alternative zu "Verknüpfung", z.B. für externe Seiten oder PDF-Dokumente.',
           },
         },
       ],
diff --git a/src/compositions/Blocks/ImageCardsBlock.tsx b/src/compositions/Blocks/ImageCardsBlock.tsx
index 775b39f..acedfbe 100644
--- a/src/compositions/Blocks/ImageCardsBlock.tsx
+++ b/src/compositions/Blocks/ImageCardsBlock.tsx
@@ -1,18 +1,14 @@
-import { Group, Media, Page } from '@/payload-types'
+import { Media } from '@/payload-types'
 import { Container } from '@/components/Container/Container'
 import { Section } from '@/components/Section/Section'
 import { ImageCard } from '@/components/ImageCard/ImageCard'
 import { getPhoto } from '@/utils/dto/gallery'
+import { ImageCardLinkFields, resolveImageCardHref } from '@/utils/dto/imageCardHref'
 import styles from './imageCardsBlock.module.scss'
 
-export type ImageCardsBlockItem = {
+export type ImageCardsBlockItem = ImageCardLinkFields & {
   title: string
   image: string | Media
-  link?:
-    | { relationTo: 'pages'; value: string | Page }
-    | { relationTo: 'group'; value: string | Group }
-    | null
-  customLink?: string | null
   id?: string | null
 }
 
@@ -20,18 +16,6 @@ type ImageCardsBlockProps = {
   items: ImageCardsBlockItem[]
 }
 
-const resolveHref = (item: ImageCardsBlockItem): string | undefined => {
-  if (item.link && typeof item.link.value === 'object') {
-    if (item.link.relationTo === 'pages' && item.link.value.slug) {
-      return `/${item.link.value.slug}`
-    }
-    if (item.link.relationTo === 'group' && item.link.value.slug) {
-      return `/gruppe/${item.link.value.slug}`
-    }
-  }
-  return item.customLink ?? undefined
-}
-
 export const ImageCardsBlock = ({ items }: ImageCardsBlockProps) => {
   return (
     <Container>
@@ -46,7 +30,7 @@ export const ImageCardsBlock = ({ items }: ImageCardsBlockProps) => {
                 key={item.id ?? item.title}
                 src={photo.src}
                 title={item.title}
-                href={resolveHref(item)}
+                href={resolveImageCardHref(item)}
               />
             )
           })}
diff --git a/src/utils/dto/imageCardHref.test.ts b/src/utils/dto/imageCardHref.test.ts
new file mode 100644
index 0000000..b0055e1
--- /dev/null
+++ b/src/utils/dto/imageCardHref.test.ts
@@ -0,0 +1,34 @@
+import { describe, expect, it } from 'vitest'
+import { resolveImageCardHref } from './imageCardHref'
+
+const page = { slug: 'chronik' } as any
+const group = { slug: 'chor' } as any
+
+describe('resolveImageCardHref', () => {
+  it('links to a page relationship', () => {
+    expect(resolveImageCardHref({ link: { relationTo: 'pages', value: page } })).toBe('/chronik')
+  })
+
+  it('links to a group relationship', () => {
+    expect(resolveImageCardHref({ link: { relationTo: 'group', value: group } })).toBe('/gruppe/chor')
+  })
+
+  it('returns nothing for an unpopulated relationship', () => {
+    expect(resolveImageCardHref({ link: { relationTo: 'group', value: 'id-only' } })).toBeUndefined()
+  })
+
+  it('uses the custom link when no relationship is set', () => {
+    expect(resolveImageCardHref({ link: null, customLink: 'https://example.org/x.pdf' }))
+      .toBe('https://example.org/x.pdf')
+  })
+
+  it('prefers the custom link when a stale relationship is also present', () => {
+    expect(resolveImageCardHref({ link: { relationTo: 'group', value: group }, customLink: 'https://example.org/x.pdf' }))
+      .toBe('https://example.org/x.pdf')
+  })
+
+  it('ignores a blank custom link', () => {
+    expect(resolveImageCardHref({ link: { relationTo: 'group', value: group }, customLink: '  ' })).toBe('/gruppe/chor')
+    expect(resolveImageCardHref({ customLink: '' })).toBeUndefined()
+  })
+})
diff --git a/src/utils/dto/imageCardHref.ts b/src/utils/dto/imageCardHref.ts
new file mode 100644
index 0000000..7147a9d
--- /dev/null
+++ b/src/utils/dto/imageCardHref.ts
@@ -0,0 +1,30 @@
+import type { Group, Page } from '@/payload-types'
+
+export type ImageCardLink =
+  | { relationTo: 'pages'; value: string | Page }
+  | { relationTo: 'group'; value: string | Group }
+  | null
+
+export type ImageCardLinkFields = {
+  link?: ImageCardLink
+  customLink?: string | null
+}
+
+// A custom link wins over the relationship. Both can be present at once when a
+// stale relationship row survives in the database (see the beforeChange hook in
+// src/collections/blocks/ImageCards.ts), and the custom link is what the editor
+// actually sees and intends.
+export const resolveImageCardHref = (item: ImageCardLinkFields): string | undefined => {
+  const customLink = item.customLink?.trim()
+  if (customLink) return customLink
+
+  if (item.link && typeof item.link.value === 'object') {
+    if (item.link.relationTo === 'pages' && item.link.value.slug) {
+      return `/${item.link.value.slug}`
+    }
+    if (item.link.relationTo === 'group' && item.link.value.slug) {
+      return `/gruppe/${item.link.value.slug}`
+    }
+  }
+  return undefined
+}