Strumming with arthritic fingers

Picked up my wife's dusty mountain dulcimer and trying to play it. Joined the group. It was a wise decision as the folks here are knowledgeable and friendly. My first problem is trying to hold the pick right. My fingers are arthritic, weak and can't hold on to the pick. Discovered thumb picks, bought a few, and they are great. I could actually strum and play some noter/drone arrangements. However, I can only strum with an away motion, can't strum with a return motion toward my body as it turns the pick away. Using the same motion makes my strumming somewhat boring. Is there any way I can use a thumb pick in a back and forth motion? All suggestions and comments welcomed, thank you in advance.

oldmdpicker