Searching for women's clothing for short woman with loose sleeves for very large upper arms. Any suggestions?

I've spent about 1 1/2 years trying to find a replacement for the Secret Treasures knit snap-front duster robes that my mother wore when she moved in with us; this brand seems to have been discontinued.

The only replacement I've found is Adonna brand from JC Penney. Mom's upper arms are very large, but she's a short person. We've had to buy XL duster robes, Adonna brand from JC Penney, which are too big around - but still the sleeves will barely shove up to get out of the way of her blood pressure cuff or to simply be loose enough to wear comfortably.

Are there modest clothing lines made for elderly women who have, typically, a lot of flab on the undersides of their upper arms? She's staining her gowns nearly daily now, and we really need a larger supply of comfortable, well-fitting ones. And she's down to 3 blouses that she can wear out in public, due to the same issue of sleeve size.

Thanks for any suggestions.