I've never heard of tearing an ab muscle through bellydance - but, there's a first for everything I suppose. After two abdominal surgeries I can tell you that resting the muscle is the best thing for healing. However, she should still exercise through walking and maybe once a week try a very light bellydance move to begin the abdominal conditioning. I know muscle tears are not the same as surgical cuts, but it's the best advice I can give. :) good luck!

Hmmm, I agree with everyone that it's strange she doesn't remember when she inured herself.
I had a sore abdominal muscle once, and I know exactly how I got it :-) It wasn't from bellydancing, but I had a cold and just got it from all the coughing!

I just kept on bellydancing, but certain moves would hurt.... I could do a chest lift, but not a chest slide and could only do small hipcircles and hip slides... Normally her body should tell her which movements she should avoid!

To answer your question, I would be extra careful with all chest isolations...

wow, that's too bad. If it's causing her "consistent pain when she belly dances" then I'd think she shouldn't be belly dancing, unfortunately. It must not have healed all the way - if I were you I'd make sure her dr. ok's her return to class before taking her again.

I once tore my right oblique, and because I was stubborn and kept dancing when I wasn't fully healed, it still gives me trouble. She can do very, very light dancing, but not much.
Rest is the key. She needs to take it easy for at least a month if the tear is severe.
Usually the only reason for tearing a muscle is improper warm up. I pulled my oblique because I skipped through my warm up and then danced. She needs to take extra caution to make sure that she is feeling very strong and limber before she starts dancing. She may need to take extra time to warm up now, and will need to do stretches specifically for the area she tore, concentrating heavily on the injured area.