My husband and I entertain frequently, and a lot of our friends have toddlers and elementary-aged children who they bring over for Shabbat meals and things like that. How do I prevent these kids from destroying my house when they're here? I don't want to overstep my bounds in disciplining my friends' kids, but I also don't want anyone to get hurt or things to break. Also, I have a new baby, so in a few years, I'll be on the other end of this issue. I don't want to say or do anything now that I'll regret later when I realize that maybe my expectations were unrealistic.
There are three relationships at play here: You and your friends; you and their kids; and your friends and their kids. You have several options of how to manage these relationships to help ensure shalom bayit (peace in the home).
If you invite your friends over by email, you can put something in your message like this: "Children are welcome at this meal. Our house isn't a great space for running around, so please bring some books and quiet toys that your kids will enjoy if they don't want to sit at the table. If you have any questions about having kids in our house, just let me know." If you have some friends with particularly troublesome kids, you could send a follow up message that says something like, "Just wanted to check in and see what I can do to make you all comfortable here." Hopefully, you'll open up a conversation about what it means to include kids in these gatherings and how the adults can work together to ensure success.
Before guests come over, do everyone a favor and move particularly breakable or stainable items out of reach. Depending on the ages and temperments of the kids, when they arrive, you can welcome them with big open arms and a few rules. Once kids are about two, they start to understand that different rules apply to different people and different places. So you can have rules at your home that their parents don't have, and you may even be lenient about things that are off-limits at home. Your rules could be anything from, "No grape juice on the couch," to "Kids get dessert before adults." Rules don't have to be negative, so feel free to have some fun creating the atmosphere that you want for your meals now and also the atmosphere you want your baby to grow up in. I would also encourage you to make clean up part of that atmosphere so that guests of all ages feel some responsibility to you as their host.
Also consider buying some inexpensive kids' books and toys to keep around your house. Even if guests do bring things from home, other people's toys are always more interesting. You can also tailor your menu to suit the kids' needs or just keep extra kid friendly snacks around. Don't be afraid to set up a cozy area for the kids to watch TV. You'd need to check with their parents first about what they allow in terms of screen time, but television typically curbs physical activity. If you do find yourself needing to discipline, try to do so only when someone's safety is in jeopardy.
The final relationship I mentioned is between your friends and their kids, and there's really not a lot you can do there without damaging your adult friendships. If you find that your friends are consistently not disciplining in a way that you find satisfactory for your home, then you may need to change your entertaining habits until the kids have grown up, or find times to entertain just the parents. No matter what you say or do now, when it's your own kid tearing through someone else's house, for better or worse, your current woes will make sense in a totally new way.