The dialogue will depend on the circumstances. In the end of Adastra it suggests the MC will spend a lot of time helping Amicus with his mission. But when they first meet, no dialogue needed, just sex please (they have 8 years to make up for)!
I'm kind of hoping that we see more of the other Sibling races once we get to the planet Khemia. Since the Jackels seem to be the most advanced of the Siblings races (but they better watch out once Humans get going) it makes sense that diplomats from many other Sibling races would be there too.
We just have to wait and see. And I'm not certain there are 16 others, that number just sticks in my head for some reason. I'd have to go through Adastra again to see where it mentions the number of Sibling races.