Anonymous wrote:Don't spend every waking moment with them even if you are sharing a house (poor planning on your part). Plan activities with your DH and kids everyday--walks on the beach, mini golf, fishing and figure out a rainy day activity. If the arguing makes you uncomfortable, grab the kids and take a walk.
I agree. Also, please be sure to invite your nephew on outings with your family so he gets a break from his parents. Maybe frame it to SIL and husband as "The kids would love some time with Jimmy and you two can hit the beach or do what you like while we take all the kids to play mini-golf" or whatever.
If you like SIL's company on her own, when she's not around her husband, find something for just you and her to do for an afternoon while the two dads take the kids somewhere. Or the dads go out to do something while you and SIL have the kids--whatever combination works and gives everyone a break. You can't do that stuff all the time, but you can set up some half-days where you are with your own family only, or you/your husband are with half of this bickering couple, or nephew is with you without his parents around.
Don't wing this stuff or you might flounder. Go online now and search for activities at the destination so you and your husband can have specific suggestions for things to do other that just a ton of hanging out time at home or at the beach. And do be sure your own family gets alone time without the other family.
Next year....lesson learned.