Anthony,
Nice to hear from another Yumet. Take a look at my 4/3/01 posting "Yumet Origin"... I think your grandpa might be Antonio, son of Yumet-Prieto and Narcisa Marin-Lassus aka Chita Marin... If that's correct then I have your grandfather having 5 siblins and not just 2... If you prefer please feel free to contact me through e-mail so I could share more. I can be contacted at:
jose.yumet@fmr.comthanks and good luck with your findings.