AWESOME, that's actually really great that you're considering it.

You don't even need to add any mods to do it, although Extra Trees would be nice

. I know the pack focuses on the bees, though, so it's not a priority to include a quest-line like that, and I know you're busy like you said.
I haven't updated yet, but I admit to having cheated in a spruce sapling to try tree breeding when I noticed that the apple and jungle saplings that are already provided through quests cross-pollinate but don't have any cross-breeds. I also discovered the industrial grafter, which would also be a good quest...
Let's say it requires quest 2 completed to unlock, and it requires you to have an industrial grafter in your inventory. The reward is a
Energetic Infuser (already in the modpack and available to craft, but no reward), used to charge the grafter from your network.
I guess also providing some side-quests to do with tree genetics (the genetics machines provided by existing quests are all that's nessesary) would be fine.
I know of the quests I suggested getting the Pollen Clusters to start it off would be easy enough; they are already provided by bees required by existing quests and are also required for other quests.
I don't THINK that my suggestions would throw off the balance of your mod-pack, and don't think it would require any extra mods or tweaks, beyond adding in the quests, their dependant quests, and their rewards, and you are by no means obligated to actually take my suggestions, since that's all they are, but I am so glad you are thinking it over.
