Although there were three people who carried the name Sarmiento in Hagåtña in 1897, all three were women, so the name is mainly associated with Sumay / Santa Rita, where one male Sarmiento was able to keep the name alive through his son.
Prior to this, we see no trace of the Sarmientos in earlier censuses, so I suspect that one single Sarmiento came to Guam in the late 1700s, early 1800s; from where is anybody's guess, though the name is Spanish and he could have been Hispanic or Filipino.
The three women Sarmientos in Hagåtña all had Taitano for a middle name, whereas the one and only male Sarmiento, who lived in Sumay, had Salas for a middle name. He was slightly older than the three women, who could have been his cousins or perhaps half-sisters, sharing the same father (Sarmiento) but different mothers (a second marriage).
The Sumay Sarmientos are better-known-as the Ñarak family, for reasons I don't know.
The Meaning of the Name
Sarmiento is a Spanish word meaning "shoot of the vine."
This is a sarmiento.