OP here. Thank you all so much for your thoughts. You have brought up more issues than I had even considered. I will try to provide answers to questions that have been asked. Her state is Illinois. I live in Virginia, my sisters in Minnesota and Texas. I mention our states just to say that we wouldn't get back to Illinois very often in case the house went downhill. Her children live in Colorado and Minnesota, so they don't get back often either. I will say that at present I would not expect her to let the house get rundown. However, no one knows what the future holds, and as posters have mentioned, this situation could become ugly quickly. Even if she had the best of intentions, what if she developed an illness that kept her from keeping the house and land in good condition?
Both her and dad's name are on the house deed. She and dad equally paid the tax bill (actually all bills) while he was alive. The house is paid off. A home equity loan...ugh I had not thought of that. Again, I do not think she would do that, but we all know how money can make people do funny things. I wonder if she will also want to share other costs - insurance, tree trimming, roof replacement, etc.
The rest of dad's very modest estate has already been distributed to us girls. I do want to add that my stepmother kept dad at home as long as she could- which saved quite a bit of nursing home money. I truly do not want this situation to ruin our relationship. It does sound like talking with a lawyer is appropriate. I think that may offend her, which would not be my intent. I would also like to just chat with her about some of these questions, but I am not sure how she will take that approach either. Ugh.
I will post updates to this thread when appropriate. Again, thank you all for your input!