FI was very close to his aunt and uncle (his mom's brother) growing up since his cousin (their daughter) was around his age and only lived a few miles away. This aunt and uncle went through a divorce about 2 years ago but are both either remarried or have a SI now. We still talk to the aunt and would like to invite her to the wedding. Do we need to ask his uncle if its ok or should we just do it? They have been together for their other son's graduation since then and there weren't any huge issues (at least between them... there's always issues when FI's family is together).