How do you contest a will and obtain a lawyer?

My Aunt recently died from a long-time illness. The past few years prior to her death she had severe dementia. Her decedents were her only daughter, 4 granddaughters and my mother (her only niece). Her original will was created in 1991 stating that her estate would go to her daughter. Her daughter died in 2001. At that time my Aunt spoke to my mother before she became ill and while in sound mind( I was present during that conversation) stating that since her daughter was now gone she wanted to name my mother as sole beneficiary to her estate. She said she did not want any of her estate to go to her granddaughters because they were all well off and my mother was not. She said she was going to create a codicil to her will. Her estate is now in Probate. The will being used is the original will from 1991 and does not include that updated codicil and/or updated will. The granddaughters added themselves into the probate as next of kin. The named Executor/Fiduciary is believed to have put undue influence over my Aunt. He named her last domicile as his own residency where she claimed her taxes which is not true. Also, in 2003 while my Aunt was not in sound mind he was put into Power of Attorney. During that time our family tried to get in touch with my Aunt and he stated he did not know where she was or anything about her since the one granddaughter took over and took everything out of his hands. But, that was a lie since was Power of Attorney and handling all of her accounts. My Aunt was a long-time resident of Cincinnati, Ohio but stayed in a nursing home until her death in Illinois. Her estate is being handled in Hamilton County-Cincinnati, Ohio.

I have a few questions to any attorney or those who has knowledge of the law and Probate. How would she contest the will? Do you think she would win if she did contest the will? My mother is disabled with health problems and is on a low, fixed income. How could she obtain a lawyer?

Accepting that everything you say is true, it is highly unlikely that you could successfully contest the will. In the case of wills, written intent is far more important than your recollection of conversations; and the fact that this person may have exercised undue influence is (a) difficult to prove, and (b) most likely irrelevant to the 1991 will.