Set Expectations. Make sure planning and financial obligations for the weekend are clearly defined. Will mom plan the service and dad plan the party? Will the Bar/Bat Mitzvah kid participate in a celebration with one side of the family and a cruise with the other side of the family? Whatever the arrangements will be, make sure everyone knows their role in the weekend.
Make Boundaries. If you’re catching heat about who you DID/DID NOT invite, remind the concerned party that this weekend is all about the Mitzvah kid. The only people who need to be there are connected to them, and if that makes others unhappy, you’re sorry but this is what your child wants. If someone is truly a threat to peace at the party, you’ll need to address behavior expectations with them ahead of time. If others are inserting themselves into planning when they’re not wanted, thank them kindly, but let them know you’ve got everything under control. Guard those boundaries.
Communicate Clearly. When certain relationships are uncomfortable (such as between ex-spouses) adults may try to avoid communication, but that’ll only delay the inevitable. Consider meeting about Mitzvah plans with a third party invited– like your rabbi or party planner – who can help mediate and keep focus. Including the Mitzvah kid in appropriate planning discussions can help keep his/her wants front and center, and remind adults the whole reason you’re doing this. If there are estranged relatives who will both be at the simcha, recommend they at least have a conversation and agree how they will treat each other at the Bar/Bat Mitzvah so that no drama surrounds them on the big day.
Attribute to Situations, Not People. Some things are out of everyone’s control, like death and major illness. If relatives are giving you trouble because you’re proceeding with a celebration when there’s a recent death in the family, reaffirm to them that in Judaism, joy takes precedence over sadness. Acknowledge their feelings (I’m sorry you feel this is in poor taste) but remind them that this weekend has been planned for a long time, and again, this is about the Mitzvah kid. Coming together as a family and making the most of a difficult time honors the memory of your loved one.
Prepare to Compromise. You’ve likely heard this one before, but that’s because it works! Saying words like “you should” are shaming, vs. saying “I need”, which makes it clear what you’re asking for. If something is really bothering you, be prepared to articulate what it is and why it’s a problem. Listen to the other person, as you’d like them to listen to you, and be willing to compromise to reach a workable solution because, (say it with me!) IT’S ABOUT THE MITZVAH KID!