How Add a widget to relationManager form

Is there a way to add a widget to the forms of a RelationManager?
I have attached a widget to a resource form through the EditPage:

protected function getFooterWidgets(): array  {
   return [
      \App\Filament\Widgets\Comments::class
  ];
}

protected function getFooterWidgets(): array  {
   return [
      \App\Filament\Widgets\Comments::class
  ];
}

protected function getFooterWidgets(): array  {
   return [
      \App\Filament\Widgets\Comments::class
  ];
}

protected function getFooterWidgets(): array  {
   return [
      \App\Filament\Widgets\Comments::class
  ];
}

This works so I added this method to the RelationManager.
no error and no widget.
Looking in Filament

RelationManager.php

RelationManager.php

RelationManager.php

RelationManager.php there is no mention of widgets like there is in

Resource.php

Resource.php

Resource.php

Resource.php .

So what to try next?