just call teh OP service center... i had two accounts, one last used about 4 years ago and then the one i've been actively using for the past 2 years. it was easy enough for merge, as my consolidated lifetime miles on my active account showed within the business day. obviously the base miles/rdms were long gone from the old account. in addition to your current linked credit + OP account, if you have OP status, i'd imagine it's best to do the account merger maintaining that one as the surviving one.

perhaps not a benefit of long time having OP or M+, but there's also the million miler status if you are spending enough time in these airborne canisters. while it seems that this sort of status will survive post-merger, no details have been released as of yet.

https://www.continental.com/web/en-U.../lifetime.aspx