Actually one thing we did for soccer one year because the coaches were responsible for putting up the nets. Got some industrial strength velcro from homedepot that was sticky back. Then cut pieces of both fussy and loops and stick them back to back. Then they were just wrapped around the posts to secure the nets. That would work for the kids too and be adjustable to whoever needed to use them.
Buying mitts that are too big is the other thing they need to do as in bigger goes up further. You can also cut off the top of a sock - like one that has gotten a hole in the heel. Then hand sew the piece of sock to the inside of the mitts. That makes them longer and they go on before the coat and that helps hold the mittens on - at least there is no wrist showing to get in the snow.