Family members recovered RDMs from over two decades ago when they reactivated as adults, the accounts I used for them when they were young children.

CO "deactivates" old accounts. CO claims the right to expire your ACCOUNT, while the miles themselves have no expiration. It's a subtle difference from the other airlines who don't necessarily expire or deactivate old dormant accounts, but regularly expire miles. Like UA.

Since the Loyalty Program management of the combined airline is run by a former UA executive, if I had to guess, I'd expect that we'll have the common 18 month expiration of RDMs for no activity, when the merged program is announced.

So if you have an old OnePass account, or your account has lain fallow for a while, I'd strongly suggest you do at least some OnePass earning activity to reset the clock, while OnePass still operates under its current rules.

I don't mind them moving to the UA/AA/DL/US expiration model, where any earn/burn resets the clock on all RDMs.

As long as they don't do it like LAN, where your kilometers expire in no matter what other activity you've had, and only LAN flight earnings reset the clock. I had to do a quick JFK-YYZ hop on LA in September to keep my LANPass kilometers in play. (Of course I turned it into an RDU-JFK-YYZ-YVR-SEA routing for various program earnings when I was just going RDU-SEA!)

Nor like AC, where I believe all RDMs expire 7 years after earning, no matter what you've done in the meantime.