So what you have is a bunch of guitar for people who are disabled or elderly and you want to teach them to play along easily. And you'e winering whether straight fretting or slide would be better?

Well, it seems to me you are on the right track to do some good work with these folks. I agree, plae a sticker or some kind of fret markler so they can find the next fret easily. Kinda like a dulcimer, it's hard to play the wrong note when the wrong frets are all taken off.

Whether to use a slide or not? I think many of your folks will be able to fret with fingers. For some the addition of a slide will complicate things. On the other hand others may find a slide easier. And others may find that laying the guitar down and playing slide lap style will be easier. Adn for your purposes you can do it all on the same guitar.

What kind of slide? I'll bet you can get a hold of some metal slides made out of a pie of metal tubing. You don't want glass for fear of dropping and breaking it. A few fairly large slides would help those hlding it lap style. Other will want a pie of pipe to stick their finger in . Have them use their pinky or ring finger.

I recently had a patient come in for therapy after breaking her left arm and having pins in the wrist. She can't rotate her wrist now. She's a fiddle player and teaches music in the schools. She is very very upset.

She won't be able to fidle for a while, so I suggested she get a mandolin and start playing it to strengthen the arm muscles and help avoid atrophy. she was amazed when I wrote a prescription to play "Irish Washerwoman" several times a day, slowly at first, gradually increase speed.

sounds like you're on track

I hope I helped

John