StepParents don't have legal rights to their stepchildren. The only rights you have to them is given through one of the biological parents. (In your case, your husband) As far as emergencies, have him fill out a permission slip for you to keep in your purse giving yourself permission for medical emergencies or whatever.
With my stepchild, I was the one that sought all medical attention, filled out paperwork, enrolled child in school, was called for emergencies etc...But I was able to do that because my husband allowed me to. Just to be on the safe side if you are ever confronted with just being a stepMother, have a permission slip available that authorizes you to do those things. I never had any problems, but some people get questioned.
If your husband doesn't already have physical custody of the child, you will need to get that done asap. If the Mother is not around a lot, file for full custody.
Good luck!
