My staff has been really ill, she was poisened with rat poisonin an she had/ has a stomach ulcer which she is on medication for, she also had long worm, she is recovering really nicely an eating very well, but she is still really underweight, her ribs, spine an hip joint bones are still visible, what can I feed her to build her weight back up?

What does the vet say?
There are herbal supplements for poisoning and for worms and stanima BUT you NEED to make sure they are compatible with the medication and all.

She won't eat anymore then she can possibly bear. She knows her limitations. If you are patient, her weight will return in a natural way but will probably take a while. Check with her vet to see if there are any supplements you can give her to build her up. Bear in mind, it isn't necessary to buy directly from the vet, their supplements are very expensive. Quite frankly, I buy my dog supplements from my local pharmacy when she needs something which is very very seldom.

Tick

I agree with Tickle... there are some gret suppliments that you can add to her food.
In addition to that there are also some weight gain specific dog foods available. But always best to check with your vet in case there are underlying health issues involved in her not gaining weight.

What has she been wormed for, a specific type or a general 'all wormer'?