Here’s a story from the September 9 1949 edition of the Toronto Daily Star about an impeding divorce in which one of the partners was the mother of child star Margaret O’Brien.
According to Margaret O’Brien’s Wikipedia page, her mother, born Gladys Flores, was a flamenco dancer who regularly performed with her sister Marissa. She passed away in 1954 of a heart condition; young Ms. O’Brien was 17.
I could find no reference anywhere to Don Sylvio.
Margaret O’Brien (born Maxine O’Brien) was seeing her film career start to wind down at the time of this article, as she did not successfully make the transition to adult roles. She did appear in a number of television shows as an adult. She is still alive as I write this; she turned 84 this past January.