Is it possible to combine two accounts?

Once, many many years ago, I created a gamer tag on my xbox 360. In doing so, I signed up for a Microsoft account. That account was linked to my xbox for many years (14 or 15 years, maybe?).

Eventually, I was asked to create a Microsoft account to use Windows services. I had switched primary email providers by then, and had stopped regularly using my xbox 360. I don't remember exactly why, but I ended up creating a new Microsoft account with the new primary email address. I don't think at this time that I knew the windows accounts and xbox accounts were the same thing.

Now today I have a problem, The gamer tag I have used for ~15 years is tied to the first, earlier account. Some purchases I made on the xbox store are on the account. However, I have other windows services which are tied to the newer account, which is also on the more recent email address which I use.

Ultimately, I would like to transfer all purchases, history, gamer tag, etc, from the older account to the new account. Effectively merging the accounts, with the new account remaining active, but the gamer tag and purchases of the old account available in the new account. I'd also like to keep all purchases, etc of the new account, obviously.

I imagine this isn't a simple ask, and will require the help of Microsoft support. Is what I am asking possible? I can prove ownership of both accounts.

I've wanted to do this for a long time now, but every time I've looked into it I couldn't find any way to do it and it just hasn't been a priority. However now with Minecraft merging Mojang accounts into Microsoft accounts, I want to keep my old gamer tag but also want to have Minecraft tied to the newer account, which isn't currently possible.

:)