How do you get that many traits through fusing? I've only ever managed to get six, four from using and two from adapting.
Well... That's the easy part actually, in this case I started with fusing focus, so you get to choose one more trait when fusing. You get TransferableAmountFromA = (TotalAmountOfA/2)_rounddown+1_IfFocus. Like if your creature has 7 traits, normally you'd transfer just 3 traits, with fusing focus you get 4 (from each side).
I used adapted tentacles with mutation (for faster filler gains) and catalyst (required for tentacle/seedling fusing) to get two final creatures, one seedling dragon (or desired recessive species of your choice) with catalyst and 6 traits in total (at least 4 wanted) and a tentacle with 10 traits (at least 6 wanted traits), and this one had seedling dragon recessive species while fusing (just to be sure...).
There is some inconsistences I can't figure out, sometimes the subspecies from the creature on the left has dominance if they are in the same tier, but sometimes the tentacles have complete dominance and wipe out their partner species. Not to mention that tentacles gain gender after fusing which might be related somehow.
Even without the focus. You can also spam filler traits with mutagen potions, so if you have something with 5 traits you want already, you can fill it up to 10 (cap) and transfer to the next creature. (You risk getting the bloodline trait tho, so I recommend save before, just in case)
Jeez... Who would thought that basic genetics from elementary school would turn me into a expert in a underground porn game? Finally it became useful for something. o.o XD