Set up of new iPhone / passcode of other phone

We have one Apple ID, with 4 phones under it.

Trying to set up new iPhone 11 replacing iPhone 7

Going through set up to transfer from old phone to new, the new iPhone 11 keeps asking for the passcode of my sons iPhone 11. That phone is not even near the new phone.

if I hit cancel that request it just goes back to the Apple ID screen, then back to asking for passcode for my sons phone.

could thee be something in his phone switched on that is making the new phone look to his passcode ?

please help !!! Thanks !!!