Here's the three possibilities for mergers. I don't really think any of them are aesthetically appealing.
I only have the most basic grasp of post-cold war european politics, but I could see there be some objections for a complete merger, both by the Austro-Bavarian Republic and other european countries.
The second one would basically be the closest to OTL, so I'm inclined to call it the most plausible one, though I really couldn't judge.
I recently heard the question being raised if the majority of GDR-inhabitants even wanted to merge with west germany, so I included the third version with an austro-bavarian merger but no german one.
