>But if they are momentarily connected to different networks (frequencies), even though they have the same SSID and same password, Apple software will see them (correctly) as on two different networks so the password will not be shared even when the password is the same on both networks.

I don't get it, how is this an issue? If both devices are already connected to the same SSID, then both devices already have the password. Why would you need to share passwords?