@rvrrat14 I believe whatever account that you create and login to when that aircraft is purchased and first turned on, will be the account it will be associated to for the life of the aircraft. I've had 2 phantoms at one point and they both would "share" the total miles flown info. They would separate the individual aircraft information ie serial, batteries, etc.
So basically I had 2 tabs, 1 for each aircraft. Both tabs shared total miles flown and i believe total flights between the two aircraft. It made it kind of confusing for me at times. That was some time ago, so forgive me if they have changed things. My experience with this is from 2017-2018.