I was looking at anold Denon file of mine for unextended 8910.
Then I wanted to take a peek at Capn Trips' cool files for extended 8910.
Randomly picked a DC file.
When RM prompted to save my file before opening the second file I answered NO.
The second file opened and announced, in the title bar, 8910 extender. That part is ok.
The rest isn't. So I saved the result as MixedUpgrade. Error log included.
Effectively, we got 2 files partly merged. But only on the DC tab. Not functions. Not buttons. Not upgrade (not 100% sure, I think Denon devices got dragged into the index).
It's kinda cute