How do I merge two Apple Accounts on my iMac?

I want to combine apple accounts. I had one for apps from years ago before family sharing existed. It allowed my family to share apps. Then icloud came out and all of us has our own account for icloud. Consequently I have two accounts and it's just stupid that I cannot merge them easily. Anybody know who to merge accounts?

[Re-Titled by Moderator]

Original Title: Merging Apple ID accounts