Nichelle,
I admire your bravery to publicly open your home life and the struggles that you have dealt with. You were open to change, asking for a new way to deal with the issues that I know you understand are not Savannah's fault.
I think what most people want for you is support for you to learn how to create a structure for your family. That structure gives Savannah comfort and help to learn that there is an order to the day as well as other priorities that have to be incorporated into the day. This structure gives your other child the chance to see that family life has a routine that is normal and creates safe boundaries, and gives you relief in knowing that Savannah is learning the routine, your other child is comfortable in the family stability, and that you can take any challenge in the day and refer back to the routine.
Having worked with street youth dealing with recovery from addiction, and no structure in how to live on a daily basis, I acknowledge that developing the routine and introducing it to an individual - regardless of age, mental developmental level, or other barriers to learning - is the most difficult challenge in starting to gain control and stability in a family. However, the routine is crucial for assisting people who are dealing with behaviour-control issues because the structure is safety. Another key point to making the routine work is posting it in a main area of the house, usually in the kitchen. Use picture magnets, coloured markers, and symbols if that's easier for everyone to recognize and understand.
This isn't something specific for PWS kids or kids in addiction recovery, this is something that is often recommended for every family. My friends use it with their kids showing the daily schedule for going to school, after-school activities, family chores, mealtimes, learning self-care (e.g. brushing teeth and bathing), and bedtime. They see the routine, they recognize it, and it becomes part of everyday life, which is the ultimate goal.
It will be difficult, but I think you have lived through the worst part of it, and are ready to find better tools to help your children become amazing people. There have been some great supportive messages from other people who have worked with or who have children with PWS, and I hope that you're able to find the resources that are available to you. You have beautiful kids, I know you love them, and I believe that when we have better tools, we do great things.
I think you can do great things.
Kelle