is this a bad idea

I might be worried that the chicks would peck at the wound as well. Maybe it would help to use that Blue Kote stuff I keep hearing about? I'm not sure I'm right, but it seemed like my chicks love to peck everything. I hope your hen's wound gets better and she can re-integrate with the flock.

 

I agree that the hen may be more at risk from the chicks than vice versa,

Sandie

 

Chicks are very inquisitive and curious creatures, and can be very aggressive when given unrestrained freedom. I have a couple of two month olds that I permit in with my three-week olds from time to time because they're very docile and patient with their tiny sisters. However, because they are reluctant to peck back when the chicks boldly come up to them and peck them, sometimes I fear an older sister might get an eye pecked out.

Your older disabled hen would not be able to adequately protect herself, so I believe it would be a very bad idea to directly expose her to the chicks.