First, see Pop-Up Text in Microsoft Word and Pop-Up Text Add-In for Microsoft Word.
Once you have the field you want with your desired display text and pop-up text, you can select your AutoTextList field and save that as AutoText, a Quick Part, or some other Building Block.
You can attach a keyboard shortcut to that for easy insertion.
Assigning Keyboard Shortcuts in Microsoft Word 2007-2021 (365)
You could then go to each instance and insert the field from your building block.
To truly automate this, you would need to use a macro to go to each found instance of "ABC" and insert your building block. Here is information on using a macro to insert a building block.
Using VBA to Insent an AutoText Entry or other Building Block