In Colorado, How A Non- Parent Can Become A Guardian Or Get Custody. Both Parents Have Unsafe Homes.

Loooong Background: My nephews parents have 50/50 custody of them through a court order. It's been like this for almost 10 yrs. Nephews are 12 and 16. Their father (my brother) has been married to a woman for the last 7 years who tricked him into marriage with a fake pregnancy. She has made it clear she hates his children. In the years she has been in his life she has banned the kids and their dad from eating, showering or being in the house except to sleep during his parenting time. My brother is under her control and doesnt stand up to her. If its not obvious she also abuses my brother in many ways. He pays all bills for his wife, her mother and adult brother who live with them. Works days and nights and she doesn't allow him to sleep. Shes also isolated him from his entire family and friends. We are essentially estranged. To appease her he's agreed to these rules so he keeps himself and kids out of the house, they shower at a gym, kids eat at an after school program until 5pm, to kill time they will stay at places like libraries, Starbucks, parks etc. If they are at the house they are forced to stay outside all day in the backyard. In the early years before banning them from the house she used to make the kids eat in the garage and stay out there until bed. Dad isn't allowed to cook in the house and had to ask permission. If mom sends snacks they are taken because their bags are searched once they arrive. They are not allowed any technology because she doesn't want photos or recordings of their treatment. Not even school computers. I could go on and on and on but the point is that home is not safe. Their mother is married to a man that beats her, he's an alcoholic and also uses meth and fentanyl. They have two children together as well. He also threatens to have his family members beat her up or threaten to give her youngest kids to his mother. His family agrees to carry out these threats. Recently she came home after work from a night shift and he started to beat her again. In the process of defending herself she managed to stab him in the arm resulting in 3 stitches. He called police and only she was arrested. This home is also not safe. Mom is leaving this man and moving out once she is out of jail hopefully in a few weeks. She's already been in for two weeks.

My sister has been given permission by the mom to have the older boys (my nephews) during her parenting time so they aren't having to stay with her husband/their stepdad.

My brother is aware of her legal situation but cannot tell his wife the boys are with our family. He told his wife the boys are with the mom's family. The reason they aren't is because the mom's mom is an alcoholic/addict and her daughter doesn't allow the boys around her unbeknownst to my brothers wife. He's at the point where he has a burner phone she's unaware of. There are already legal issues between his wife and their mom because of how she treats her sons when they're with their dad. My brother is supposed to be paying child support but he quit his job 4 months ago and is now working two different jobs and not reporting it. His wife recently came up with the idea of going for full custody so they can get child support from mom. It's simply a money grab. Not because she cares about the children. Pure greed.

Mom has heard this from jail and wants to file for full custody herself. She also supports 50/50 custody to my sister. With her being in jail the process is confusing.

What we need help with is what is the first step my sister needs to make to get the kids under her care legally? Colorado has a self help page and forms but we don't know where to start. Has anyone had experience where a non-parent has to assume responsibility?