Just went through some books I read 40 years ago and run over the 29 mating schemes of #JohnVarley s #Titanides.
Two pages of the possibilities you have if you have 3 sets of genitals, the egg has to be fertilized twice and transferred once.

Sorry, there is no description in the pictures. I just don't know how to describe that.

https://en.m.wikipedia.org/wiki/Gaea_trilogy