John Boat, before I forget to ask, how are your musky doing?

Anyway, if your friends enjoy catching crappie, this may be too extreme, but the most common recommendation for crappie in a pond is to remove every one that you catch as you have already stated. With 10 acres (which I believe is a good size), you could remove every crappie you catch and still have some big crappie in there. I think it's also said that crappie affect LMB growth by competing for the same food that LMB would eat.

You are most likely right about the LMB being overpopulated, and the need to start a LMB culling program.

Once your friend's LMB get bigger, I believe they will also help control the crappie population.

These are just my opinions.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."