Swimwear elastic would help if you don't want rip out the hat, go to a smaller hook size, etc. It has 3 times the stretch of regular elastic, comes in skin color, and doesn't ever bind the skin. There's also a shear elastic product that is unwoven, stretchy, and very comfortable. It's translucent and paper-think, that's the best description I can give, except that it's about 5/8" across, whereas swimwear elastic is just under 3/16 of an inch. If you make a covering for regular elastic, it would work in a pinch, but that's a lot of work to go to, but covering for comfort is something you want to do for your sister you care about.
Swimwear elastic is more giving than lingerie elastic, but lingerie elastic comes in a plethora of colors if you find the right shop. Unfortunately, things change over time, and yesterday's wonder product finds itself in the trash when companies go under or change hands, or even when fashion changes.
Oh, well, that's life. I had foot cramps all afternoon so took a nap. I was late on my morning meds, just flat forgot to do it in order to continue my little tasks of trying to organize my embroidery stuff. A 2-hour nap cancelled the severe foot cramps, but now it's time for the night meds or else. So I didn't get to do all the things I wanted to do today, or even to read posts.
Tomorrow has got to be a better day, the Good Lord willing. *sigh*
Edit: something happened to the first part of my post. ??? Wonder why my computer is being so temperamental lately. Well, I don't know. It's bedtime for me.