Christy,
What a dilema! I think you need to sit down with your assistant and have her come up with a clear schedule (I know that you have probably down this w/ her). If the job was explained to her that she has to work every other weekend and even then only a few hours, then you may have to let her go since she isn't living up to what the job requires.
It sounds good that she wants to continue working three days per week: have one (or two) of those days be her weekend that she would normally work. It doesn't sound like the weekend hours are too difficult.
You might have to let her go if she still can't live up to the verbal agreement for employment the two of you had. Make sure what you told about her hours is put down in writing in a memo. Even after the fact, a memo is binding...
Tell her in the memo: here's what we agreed to in the interview about working hours, benefits, vacation, etc.
In the end, I don't honestly believe she's there for the right reasons and will weed herself out if she's not let go first. You need to talk to your admin. about this, if its legal... Are there any restricitons for work she has from when she was hurt? It makes me wonder if she's only allowed to work three days per week. Something to think about.
Good Luck!
Trish
(Gaelicpaddy)