Some of the tabloids refer to her as a mom, but make no mention of the actual child, so I’m not super sure of that detail.
I see that the WSJ openly mentions that Swing told the FBI that she assumed he gifted property to her because of his former romantic relationship with her mother, but nobody is asking (or answering) whether he is her father.
A former relationship with Swing’s mother at least explains how he knew Swing. Warner’s mother probably would have mentioned Swing being her granddaughter if Swing was Warner’s daughter.