First of all, is the house in all three names right now? If there was no Will, was there a TOD?
I am in almost the exact same situation right now!! After my Mom passed, my Daddy put the house into a "Transfer on Death" deed so my two sisters and I could own it without having to pay taxes - that is until/if we sell it. I didn't see any problem with this. He then left us enough money to pay taxes, etc., and to do any repairs so we could sell it; he didn't really want us to rent it out (not sure why). But then after my Daddy passed, one of my sisters turned into a Witch with a capital B!!! She has fought me and my other sister on everything and refuses to help with anything! It's been a nightmare - especially since I'm two hours away and trying to deal with all this!
I am at the point now where I don't care any more and just want to unload the hassle and headaches of dealing with her - I would be willing to put the house in just her name and then she can do whatever she wants BUT I would have a lawyer draw up some type of contract so that when the house is sold, I would be given my fair share, minus any of her own money she would put into it.
If you still want to have your say as to what happens with the house, I would NEVER let her put the house in just her name. I'm not sure this can even be done WITHOUT a lawyer so no need to worry about her doing anything like that behind your back. As for taxes, either split them three ways, or if she's living there full time, let her pay a bigger portion. I hope she's paying the utilities while living there and doesn't expect you all to chip in - that wouldn't be fair?
Whatever you decide, I would at least consult with a lawyer that is proficient in dealing with this type of stuff and get your questions answered before you do anything.
Good luck!!!