Sync() in One to Many relation

There is nothing like that.

You can just do somethin like this

$post->comments()->delete();

$post->comments()->saveMany([
    new App\Comment(['message' => 'A new comment.']),
    new App\Comment(['message' => 'Another comment.']),
]);

I can't delete them all because there is a different relation with this entity in a poly pivot and the id will change if I do this.

So to explain better: Entity A haves one to many relation with Entity B. Entity B haves a poly relation with Entity C and Entity D.

If I delete them all and create them again id will change and poly will not work anymore.

How I said, there is nothing as sync() for one to many.