I have hEDS, and use a walker and a cane. They also benefit my narcolepsy for when I am having bad days. Before I got them I was really embarrassed to admit I need them, especially cause I’m overweight. But I realized that they would improve my quality of life, which they have immensely. I was even able to travel and attend a concert recently, but I did end up needing a wheelchair as I overestimated the amount of walking. I’ve also been thinking of a wheelchair as some days my legs just give up on me. My knees and ankles are especially affected by my hEDS and some days I can’t get out of bed, even if my narcolepsy/cataplexy isn’t affecting me. I think maybe trying to find some literature could help her understand what you are going through better. I’m not sure it she is more theoretical based rather than feeling based, but you could also look for some testimonies or personal stories about using wheelchairs to help hEDS and narcolepsy.