In a statement released by their attorney, Jerry and Joey Banks said their father was ill at the time Regina Rice had him sign a power of attorney, a health care directive and a will giving everything to her.
Rice responded in a statement that Banks trusted her to carry out his wishes, some of which were during his lifetime and others after his life, and made her promise to adhere to them.
"I find it quite interesting that she did not tell anyone that she had an attorney write up a new will," Jerry Banks said.
Joey Banks said the family thought Rice was helping and watching over "Mr. Cub" while he was in Chicago.
Family attorney Mark Bogen said that only after the funeral did the Banks family became aware he had signed a new will during his illness.
A provision of the will, signed and dated Oct. 17, says: "I am making no provisions under this will for wife or my children, not for a lack of love and affection for them and for reasons best known to them."
Bogen said the family will vigorously fight the will.
"It is understandable that Ernie's family is concerned at this very sad time," Rice said in her statement. "However, the record, and those closest to Ernie, will dispel any iota of concern regarding my relationship with Ernie and his trust in me to carry out his wishes."
Rice went on to say she will not participate in any verbal jousting with Banks' family or do anything to tarnish his legacy.
Before Banks' death, family members frequently spoke to Rice because she made it difficult for them to speak directly to him, Jerry Banks said.
"At the funeral of my father, I went out of my way to praise Ms. Rice and her son for helping my father." Joey Banks said. "What I did not know at that time is that for at least six months prior to my father's death, in my opinion, she was using him, manipulating him and controlled him."
The brothers' comments are their first in a dispute that first centred on what should be done with Ernie Banks' remains. Estranged wife Elizabeth Banks went to court to prevent Rice from having Banks' remains cremated.
Rice wanted Banks' remains to be cremated after his death last month at the age of 83, according to documents filed by Elizabeth Banks' attorneys on Feb. 2.
Attorney Howard Golden said Elizabeth Banks has thus far prevented the body from being cremated.
But it was unclear where exactly the body was taken, with officials of Graceland Cemetery, just blocks from Wrigley Field, saying he wasn't buried there. The funeral home that handled the Banks memorial says it doesn't have his body.