My 8 and 9 yr, old shih zhu poodles are hostile to a relatives puppy yorkie tea cup.
They will not socialize at all. Why?
Hi If they've not had a lot of socialization experiences or are unfamiliar with interacting with a puppy, then this is to be expected.
As they spend more time with the pup they may adjust and eventually accept, or at least tolerate, him/her. But if it's a whole new experience for them then it could take some time!
If the puppy is coming into their home then there is likely also an element of territorial behavior here and you may find they're more friendly on neutral ground, or in the puppys' home.
Unless there's outright aggression, it's best to let them all figure this out in their own time, only intervene if you think the pup is in danger of getting hurt. But you can correct your dogs if they are openly hostile or growl/snap.