My Geos were a bit smaller than the menerambo, and is probably why they didn't try to dominate. And there was 3 or 4 of the Geos in the tank with 6 menerambo, so they had there own group dynamic, which kept them busy with each other.
One thing about menerambo (at least mine).
They did not like any sort of change in stock, once the hierarchy was set.
Any change, any addition of cichlid stock, or subtraction seemed to cause immediate chaos.
I pulled one menerambo, at a certain point, and within hours, all menerambo started to kill each other.
Another time, a pair started spawning, and I thought if I pulled the others, the eggs would have a better chance.
As soon as the others were taken out, the pair bond failed, they ate the eggs, and started to kill each other, until the others I had pulled, were returned.
These are a group oriented fish, with a complicated inner group dynamic.
You can probably add or remove non-cichlids dithers at will, but any cichlid changes I tried, usually ended up disastrous once they had matured and their hierarchy was established.