I'm not saying this angrily- but trolls do have to mix their material beforehand with a partner, then that bonded material is taken in a pail to the mothergrub. We know this because it's mentioned on page 004296 that "The pails are all offered to the mother grub, who can only receive such precombined material." and also "Especially strong matesprit and kismesis pairings yield more dominant genetic material. " so the intimate pairings beforehand are very important to troll reproduction.

That’s with thousands upon thousands of trolls/ genetic material tho. The intimacy factor is likely not as big a deal with only half a dozen samples.