Apple id problem

No action you can take will result in merging two Apple IDs. The best you can do is:

to create a new Apple ID https://support.apple.com/en-us/HT204316 See the data implications below.

Some of these things will apply to your situation even though you are not changing your Apple ID: What to do after you change your Apple ID or password https://support.apple.com/en-us/HT204071

 Keep in mind that some things available under a first Apple ID will not be available under a new Apple ID. For example, you won’t be able to transfer anything purchased from the App and iTunes Stores to the new ID. And, there are other issues to be addressed.

And see what Eric Root says on this matter here https://discussions.apple.com/thread/251343949 and

what Winston Churchill says about it here: https://discussions.apple.com/thread/7452747

As stated above, you can't merge Apple IDs. If you only want one ID, I suggest you not create a new ID because that would give you 3 IDs. You can delete the phone number ID and you should be able to add the number to the email ID as a trusted number.

All purchases made using an Apple ID are tied to the ID. Delete the ID and you will need to download them using your new ID.  Make sure you sign out from the places in the 4th link before deleting the ID.

How to delete your Apple ID account.         

Apple ID – How to Delete.        

Delete Apple ID (new).         

What to do after you change your Apple ID or password - Apple Support      

To add the number, log into the email ID after the other ID is deleted.

Apple ID - Manage