Originally Posted by
simpleSnow
Yeah I've been thinking I will just set up a separate FFP account for my EU passport. With United for instance, you can actually transfer miles from another account, there's just a transaction fee, so I can transfer the miles I accumulate on my EU passport account to the main US one which has more miles, so it's not too bad. From United:
It's a bit of a hefty fee, but hey at least I can accumulate most of the miles in one account and simplify my OLCI for EU trips. It's the price I pay for my name dynamic

but when ETIAS comes live I'll try one time buying it with my US passport and seeing how much trouble it is with airline rep, maybe it's not as bad as I fear.
If you get an A3 account each with their own distinct email address and achieve *S or *G status in the program with an A3 account, you could set up a together account that merges the miles together for free.