I invited my half-brother, his wife, and their two kids to my wedding. Their son is my ringbearer. They are staying at a nearby Airbnb for the event, and recently relayed to my mom (not to me) that my half-brother's parents are also coming along with them to stay over. The reasoning is that my half-brother's mom and his stepdad would watch over their youngest kid (two years old) after the wedding ceremony back at the Airbnb. His wife wants the kids close to her, so this seems to be her plan so that she, her husband, and son can stay late at the reception while his parents are watching the daughter nearby. This is rather awkward and rude to not ask me first, because I know that my dad will be livid when he sees his ex-wife and her husband approaching our reception area to pick up the daughter. The reception is in a very open and exposed area under a tent, so anyone coming will be seen. Also, I did not invite them or even imagine this situation of them showing up, which makes it even more uncomfortable. Even if they are only there briefly to pick up the daughter, that still causes tension anyway. Should I contact my half-brother and sister-in-law now to ask that they be discreet? (It is a bit awkward in the first place since I was never told by them.) How should I approach this graciously?