New cellular attached with new phones.
Set up one.
Watch - wiped old watch kept the cell plan. Set up i17, the set up the watch. 1.5 hours with Verizon trying to get that number share to work. Had to setup a brand new number share.
Setup 2 wiped old watch kept cellular paired new watch to old phone. Set up the new phone, wiped new watch the paired with the new phone. No issues.
Setup 3
wiped old watch kept cellular paired new watch to old phone. Set up the new phone, didn’t touch the watch. Didn’t re-paired but 3 hours later I was fully paired. I have no idea if that is a new feature.