My wife is afraid my sd will fail so she keeps her here. Wife and I are in our fifties, our step daughter is 32 with an 8 year old and a 2 year old, by different fathers.  Sd has made one bad choice after another and I think now has realized this. She is working, kids go to daycare, she has felonies so she can't get assistance, but she qualified for help with the daycare through another program. She supposedly pays 50 dollars a week to my wife to live here, I don't think it is consistant. 
I don't know what is going on with sd  bills and wife says it's none of our business but I feel like if she's asking us for help by living with us then we should know and set up some kind of plan. I honestly feel like sd is comfy and wife doesn't want to make waves because of the grandchildren. We have helped sd with a car and repairs that I do to keep her working, not to mention money to help with other things that have cost us a few thousand dollars. I'm so afraid this is killing my marriage that I shut down, but I know it's getting to that point.

Im know this is all over the place, but there is so much going on I couldn't possibly get it all in here. Bottom line is my wife is enabling my sd and I can't get her to see that she needs to get motivated for the plan to get her own life. 
I love my wife adore my grandchildren to no end and care very much for my sd we have a pretty good relationship, but she seems like she's god where she's at. I want her to succeed and am willing to help but I need her to know it's time to get her shit together without blowing up and ruining things. 
She's been living with us for 3 years and needs a reality check.