This and that argument vs those arguments over there and then there’s that theory vs that theory and so on and so forth.
One thing can be made clear…
Zentraedi loved Human culture!
As they got used to it and began settling down, trying to figure their paths out in life, there are good chances that many began to do things that would eventually result in children.
No doubt they would have been frightened at first. Confused as hell no doubt. They would be out of their depth and don’t even get me started on how they could even remotely begin figuring out the concept of a Family.
In the end, Zentraedi children and Human/Zentraedi Children would have started to be born. Given enough time and decreasing issues, the inevitable intermarriage would have caused pure Human and Zentraedi to vanish. In their place would be, as one author over on Fan Fiction dot net has noted, Terran.
Which would take a few centuries, no doubt. You can’t wipe out anything like that, short of hunting them to extinction.
So we can write that one off.
In the novels, it’s implied and then stated that a single individual was able to barren all Zentraedi and begin wiping them out. But those that left with the Expedition, survived to regrow their population through natural means.
The reason for this individual, who was it? Zand?
Zand’s actions was to become the next Robotech Master and so he needed a means to achieve this and so Dana, as the first, was his ticket to godhood.
And is the highest load of BS I can imagine.
Welp! Got work. More later.