my mother want to revoke donation of properties to 2 grandchildren

My mother wants to revoke the donation of properties to 2 grandchildren without informing the other 3 children, except for another child who is the parent of the donee grandchildren. These properties she inherited from 2 other children who died without descendants. She forgot about donating the property, which is currently leased to a company, and on her last year, wanting to sell it to finance her failing health and to divide the rest of the sale among her surviving children. Unfortunately, she died on the year she waited for the donees to sign the revocation of the donation...evidence is the unsigned revocation and a video of her wanting to revoke the donations addressed to the notary public who notarized the donations.