How to raise twin 8 year old boys with disabled parents?

I am the oldest daughter of the disabled mom in question. I was born as a normal child and raised to be a very smart person, by my grandparents despite the fact my mom has cerebral palsy. She has the intellect of a 6 year old and she can do her adl's but cannot function with IADL's. Now I am in my 20's and now I have 8 year old twin brothers. They are become quite troublesome, stealing and taking advantage of my mom. The father isnt around, he has CP also. How can they be raised in an environment where it is safe and nurturing. Despite my mom is and overall good mom despite her condition, she cannot raise them alone because of her disablity. My grandmother is getting old and there is only so much she can do before she is extremely tired, yet refuses to get any outside help because everything is under control as she put it. But I am worried about my brothers as they get older. They have no male role model influence except my uncle who comes around once a month. They are involved in sports, but thats it. They are being raised as if they are women. What can we do about this