Protective dogs

My husband and i are the only ones who can grab our son from his crib/ bassinet. If family is over and they want to pick him up my dogs put them selves between them and where he’s sleeping. They don’t get aggressive but they don’t like people grabbing him. If we hand our son off to people they don’t have an issue with it. They love everyone and are gentle with everyone. They were both protective over me while i was pregnant, and they are so sweet and gentle with our son. I honestly think that they think he is theirs lol. Is there anyway we can work on this with them? They don’t act aggressively so I’m not worried about that. I just feel bad when family is visiting and they want to pick him up from somewhere.