As a convert to the Faith who is also a mom of 8, I would not stay with my IL’s if I were in your situation. My family of origin has some very loose morals. Over the years, I thought it would be ok if I practiced my beliefs, yet still exposed my children to these other worldly lifestyles because these people were “family”. I was absolutely wrong!!!
One of my older children has taken up cohabitation, saying it’s what works for (him/her) personally. Told me that this is what people do, even Christians.
My sincerest, most humble advice to you is have grandma and grandpa come visit you. Because what Mayita said is spot-on. There’s a mighty good chance that exposing your children to such a lifestyle will send them the message that you condone it. My young adult child told me that very same thing. If it was so wrong, then we had needed to stay away from the family members doing it.
This sounds hard and judgemental, but it isn’t. I think it might be a perfect example of “being in the world, but not being a part of it.”
You have to protect your children. It is your God given responsibility.
As a middle aged adult, who went through this chaos with her own family, I have to say that if grandma and grandpa can afford the physical and mental energy to house an adult child and his pregnant partner, they certainly can make the time and effort to go see their other small grandchildren out of town. I say this from experience as a daughter who would load up a van full of kids to go see her parents (and the crazy, unhealthy lifestyles of family members who were enmeshed with them) . The wise choice would have been for my parents to come to us. It’s how I prefer it now, yet my healthy parent doesn’t come over to see me or my kids and it isn’t because of my other sick parent.
If your IL’s care about your children and genuinely want to foster a relationship with them, and their daughter as well, then they need to come to you. (After all, you are the ones with the small children who shouldn’t have to experience a disruption in schedules every two months to visit grandparents.)
I pray that you and your wife can reach an agreement on this issue. It seems like she might be facing some familial challenges in the future. I pray that she comes to know that she can remain strong in her Faith, practice her beliefs and do what’s best for her children at the same time. Prayers of peace, wisdom, and conversion (IL’s) for you and your family