The specific details may vary from state to state, but usually the so-called "life tenant" – the boyfriend – is obliged to maintain the property. If your mother granted him his rights through a deed, you and your siblings would not be able to evict him if he violated those obligations. You might have a legal claim against him, which would be worthless if he doesn’t have any money to pay it. On the other hand, if his life interest is granted through your mother’s will, you might have additional remedies, depending on the wording of the will.
Deeding over your interest to the boyfriend -- assuming that the boyfriend’s right’s are in a deed -- might be a good solution. A local attorney could advise you better on this. To find an attorney near you, go here: http://www.elderlawanswers.com/elder-law-attorneys.