saveRelationshipsUsing on custom page form.

 public function form(Form $form): Form
    {
      return $form->([
        TextInput::make('name'),
        Repeater::make('cover_images')
            ->label('Covers')
            ->relationship('coverPhotos')
            ->schema([
                TextInput::make('image')
                    ->label('File Path')
                    ->required(),
                TextInput::make('note')
                    ->label('Note'),
            ])
            ->saveRelationshipsUsing(function ($state) {
                dd('saveRelationshipsUsing', $state);
            })
    ])
}

 public function saveAction(): Action
 {
    return Action::make('save')->action(fn() => //...);
  }

 <div class="mt-6 gap-2 flex">
     {{ $this->form }}
      {{ $this->saveAction }}
  </div>