Second, your daughter. In almost 25 years of working with sleep disorders, EVERY single Down's Syndrome patient I have tested (ranging from early teens to adult) has had obstructive sleep apnea. Most of them adapt well to CPAP and those that live in a local home take pride in their CPAPs. You might be able to solve your problem and, at the same time, help your daughter by having her checked for sleep apnea.
I know my daughter has sleep apnea and I took her to get a sleep study but she wouldnt follow thru. Marissa is not "most of them" that adapt well to cpap. She even has problems with tags on her shirt much less a mask on her face. But, I'll keep praying.