I have found (and been told) two main rules for successfull breeding trio's of PM is to have 1 cave/log/pvc tube in the tank. And second have 1 male per tank. I have observed quite a few orangespot/peppermint spawns (even videoed some) and the male chases the female into the "nest" so having multiple "nest" sites can make his job harder.
Just what I have found anyway. Also on the fungus side I have had more success seperating fungus eggs from spawned egg clumps than just leaving them to nature. You may loose/pop a few seperating but it is better than loosing the lot.
Good luck and congrates
Kind Regards
Gavin