family bonding
Two or more family members spending quality time together. They don't need to be blood-related, but it should be clear that they are family.
Don't use for images with family members that aren't interacting with each other in any meaningful way. Don't use for incestuous situations either.
For the reverse, where family members do not get along, see can't choose your own family.
For familial bonding where the only family members are romantic partners, use couple instead.