My fiancee has two wonderful children from his first marriage. We have joint custody and are supposed to only have the kids on the weekend but because their mom is a flake among other things, she usually only takes them a few days during the week to "justify" child support. The kids are 4.5 And 6. We want to get full custody asap but are nervous about doing it because of what she might do to the kids while we wait for court proceedings. Currently, she has no job (and has never had a job) and her bf was fired a month ago after they went on week long vacation to a hippie festival and Vegas. Before when her bf did have a job, she would make the kids wake up before 6 am to bring him to his job because he has w dui's cannot drive. The kids are miserable there and hate going. When they are there, she sleeps during the day so they are left to fend for themselves. The don't get fed breakfast and if they do eat lunch is usually random snacks. They play video games and watch movies all day. She smokes inside the apartment with them. She never takes them to the park a block away from their apartment either. At the beginning of the summer she wouldn't let us sign the kids up for summer activities because she didn't want to drive because she was "sick of wasting her time." lucky she changed her mind an hour before the lessons and I hadn't called to take him out of the class. She doesn't take them to the doctor or dentist but freaks out when we make an appointment so she will change it and then not show up for we have to miss work to take the kids because she makes appointments during times she thinks we can't go. The kids are very washed there. When the 4 year old was 3, she came back from spending a random week there with a scab on her head and missing hair there because she would get bad cradle cap if she wasn't washed everyday. She got the scab because she would itch it and subsequently lost hair in that area too. Their mom can never give us an actual day she will come to get them and now that her bf isn't working, she won't drive to get them herself because it is inconvenient for her and she won't drive "just to get them." the kids come back home in clothes they were wearing 2 years ago. They just look awful and dirty. I feel like a terrible person when I have to let them go there but I can't do anything.

She does drugs, drinks and drives, has been diagnosed bi-polar, and is a narrisicest*(sorry can't spell right now)

This isn't even everything that has gone on. There is so much more but too much to write. In the end, my question is it anyone has any advise on what we should do to convince her to switch custody (she currently has residential because my fiancee didn't know how he could keep the kids if he was working all the time) or to get full custody. The kids are suffering and if we just forced her to keep them the 5 days she is supposed to then I know it would be easy to show a court she is unfit but there is no way in hell we would let them suffer more because something really bad might actually happen and they don't deserve that. Any advise?