Transferring purchases from one Apple ID to another.

I'm an old customer. I have all my purchases on one Apple ID. That's my iTunes Apple ID. Another Apple ID has all my iCloud properties (email, 200GB storage, etc). That's my iCloud Apple ID.

I've run this way for years. I have seen some odd behaviors though. I suspect Apple doesn't test this configuration very well.

Has anyone heard of Apple transferring purchases between Apple IDs? I'd like to transfer all the purchases to my iCloud Apple ID. I have full control of both of them of course.