I came in too late yesterday, so I’ll add my bit today.
If you live in some barbarous, god-forsaken, hell-hole where the RSPCA doesn’t operate and declawing is legal, check that cat is desexed, chipped, and vaccinated. (The RSPCA does all these as a matter of course.)
Family should meet and greet cat before you decide. Talk quietly and calmly (not squeaking) all the time you are taking cat home. Give the cat plenty of opportunity to hear everyone’s voice.Offer food as soon as cat gets home. During the first few days, everyone should offer food, so that cat gets the idea that everyone is friendly.
But Happyish one anyway.