My FI and I are working on the guest list and we have one very hairy situation that absolutely has to be resolved. His father's divorce from his third wife was finalized a month ago, and we're wondering what to do. FI has 3 half-siblings from that marriage, as well as 2 from his mom's intact remarriage. So should we invite the kids and ex-stepmom and be extra cautious about seating? Should we just invite the kids since FI's mom's kids will be there? We're suspecting the now ex-stepmom is likely to turn down an invitation knowing her ex-husband will be there, but how do we work to alieviate the tension if that is not the case?