Sponsor on benefits?

Hi,

My wife is an american citizen and I am a U.K. citizen living in Northern Ireland.

I am told that I can not sponsor my wife for a spouses visa until I can prove that I can support her when she is here, I am told I need to prove that I have at least £106 per week extra in my bank for 6 months before I can even apply as a sponsor. I have been looking for a job for 9 months and have been unable to find a full time permanent job that will qualify me to be a sponsor, and there is no sign that such a job will become available to me at any time soon.

My mother is on DLA and is getting a pension, she has more than £106 per week coming in to her bank account and is, under normal circumstances, able to hire a helper to aid her daily and to pay them a wage.

Is it possible for my mother to act as a sponsor for my wife or even to hire her and sponsor her for a working visa?

My wife has a sister in the states with a lot of money, is it possible for them to sign an agreement that they will support her while she is here to get around the maintenance requirement?

Any help is greatly appreciated.