Is it okay to use embroidery floss to do some hand quilting on a quilt that has embroidery on it already? And if so how many strands wouls you use?

I have. It works okay. Make sure the floss is color fast. I use 2 strand. Quilting thread will be easier to use.

I would use quilting thread. It's stronger.

aurfil has a heavy weight thread that is for embroidery.

I think if you use more than one thread you'll be fine. Remember there are no rules, make it how YOU like. Good luck!

I have successfully used 2 strands. As Purplequilter said, make sure it is colourfast.