Sources directly connected to Ryan tell us ... the actor was all set to do DWTS but dropped out because Nancy has said bad things about his son Redmond, who has had chronic drug problems, and also suggested he was a bad parent.

But Grace tells TMZ, "We have never covered Mr. O'Neal nor his family on our show," adding, "I hate that he dropped out of DWTS; I would have loved to compete with him and wish him the very best."

Grace says she considers O'Neal to be one of the great actors of our time and she finds his relationship with Farrrah Fawcett "an inspiration to me."