There are two different processes. One is meant to merge (permanently combine) two ThankYou accounts owned by the same person (or by spouses). The other is meant to share a specific amount of points from one ThankYou Rewards account with another. The accounts can be owned by anyone.
Which do you have in mind?
Maybe it's the later?
I have 60k on Premier account and 55k on Prestige account.
I should share/transfer my Premier points to Prestige points so my Prestige points become 115K and I get full value of the Prestige points on flights?
When I click on the TY program on my Premier or Prestige card account online, it shows the points I have on 2 of these cards and have option to "combine".
That combine means sharing? and if i do that, the points expire in 90 days?