How does one conquer Native Americans and not loose diplomatic points?

Question

So I am playing as Florence and thought it would be interesting to establish a foothold in Mexico. So I declared war on one of the smaller nations to gain some land first before I continue. However, it seems that they're all connected through vassalisation so actually the result was that most of Mexico declared back. I was easily strong enough to beat all of them and win the war.

But the fun started after the war. In the peace treaty I took Tenochtitlan as well as many other provinces (as many as I could since I assumed that they would become a colonial nation as soon as I have at least five of them). That not only resulted in massive overextension of 114%, but also granted me the "privilege" of taking Aztec vassals as my own vassals. Now I have 5 new vassals in Mexico, which along with all the other relationships in Europe adds up to 9 diplomatic relationships in total.

Overextension I think I can manage by coring five provinces, and letting the colonial nation deal with them. However, having so many vassals has killed all diplomatic points that I generate (you loose one diplomatic point for every relationship over the limit, in my case limit is four so I am five over the limit). To make matters worse I am not allowed to release them until the peace treaty expires. In 15 years...

So is there any way for me to avoid not generating any diplomatic points for the next 15 years? I should add that I am playing ironman. Was there any way for me to have avoided this fate altogether and still conquered Mexico?

Answer 1

The only way to avoid your situation would have been to not fully annex the Aztecs. This is largely undocumented, but fully annexing an overlord will transfer all of their vassals to you. Next time, you get in such a situation, you will be able to make a better assessment. If you take on vassals, you must consider, that each will take a diplomatic relation and that each relation over your limit costs 1 diplomatic point per month.

The main mitigating option you have is to sever other diplomatic relations (alliances and so on). Or try to get in a war you lose and offer to release your vassals as tribute. The former isloates you in europe, the latter isn't guaranteed to work, as your enemy may not care about vassals in central america.