I don't think it's recommended. But if we have a bunch of male and female mbuna in a tank, then fry getting eaten probably happens more than we realise.
After shutting down my fry/grow-out tanks I left all holding females to spit in the main tank. Almost all fry were gobbled up immediately. Not an issue whatsoever, even with fish classified as strict herbivores. In nature, fry are consumed all the time, along with anything else the fish can glean from their environment.
I am guessing here, but if you can catch all the female mbuna. That are holding fry, as fast they can reproduce. With out striping the tank clean, and draining to fin level. Then you probably need more hiding spots for them to proliferate properly.