handicapped duck

Any info. on Pekin Ducks that have become unable to use a leg appreciated.
I have a 4 yr. old female duck.Her name is Big Duck. She has had leg and wing problems from day one, but has always recoverd from right leg problems. Little Duck who was her companion for the first 18 months, suffered from splay leg. I kept her legs tied together{monitered her leg tie several times a day}and she did fine for almost 2 years. We did lose her due to other problem. Big ducks not walking started 3 wks. ago. I make sure she eats and drink but not as well as I wish
she would. Big Duck has water therapy everyday, spends time everyday on the grass. I also keep backyard chickens. We have a rooster and hen and I think the duck really thinks she is a chicken. We have lost 3 of the chickens due to age, Big Duck does have anxiety if she can not see Cocoa and Matilda. I have seen improvement in Big Duck in last 3 days, she is now standing at times on both feet, but not walking, and have increased number of times I put her at feed and water. Big Duck is in good spirits. So I have hope for her.