Since there were a couple of instances in a playthrough I did in which Lena was faithful to Ian and kept "not kissing" Holly by "vibrating away", Lena inwardly entertained the idea of a three way relationship. Not a threesome, but an actual relationship. As I am sure you know, there are planets on which some species require multiple sexes (>2) to come together to procreate. So I believe EK will provide that option. For the "pregnancy people", I believe Holly would be the incubator and the offspring would develop from a triploid zygote into a phenotype consistent with that type fertilization; two vaginas with a modestly sized penis in between. Was that what you had in mind?