How do we tell the parents of our child's friend that we do not want to hang out?

My middle school daughter has been friends with this girl for about a year and will go to school with her until graduation. The parents, who are both recovering meth addicts and felons, have began inviting themselves over whenever their child comes over. Mom has no teeth and smells of urine, gossips/complains about all the people in her life. Dad can't keep jobs, is always fishing for pity, and is mentally about 12 years old himself and none of us have much in common but they continue to invite themselves over. They live in their Granny's back yard in very poor conditions and have made comments about moving into our home since we have enough room. I do not know how to handle this especially since they've recently began attending our church and my daughter will not want to lose this friend. via /r/Parenting http://bit.ly/2HRwPfM