Have you seen the info at Texas Tombstone Project, Hidalgo Co., Brewster Cemetery transcription - contains some history on the Brewster, etc. families.

ftp://ftp.rootsweb.com/pub/usgenweb/tx/hidalgo/cemetery/brew...

Gravesite transcriptions at link above - here is the History from the site:
HISTORY: Brewster Ranch Cemetery is located in Los Toritos (Little Bulls)
Land Grant, two leagues of pastureland awarded to Maxiomo Dominguez by the
Mexican State of Tamaulipas in 1834. In 1912, William R. Brewster (1869-1953)
bought the first 40 acres of his Brewster Ranch from David and Emma Box Bravo,
and later added 90 acres purchased from Lina Box Bowyer. The 140 acre ranch
extended from the Rio Grande to the Military Highway (US 281), then a gravel
horseback trail. Here Brewster kept horses and cattle.

The El Sauz Ranch of attorney, US Customs collector and Confederate veteran
Lina Helen (sic) Box was adjacent to Jackson Ranch, and the Brewster, Box and
Jackson families were all members of the first Methodist congregation in
Hidalgo County, founded in 1874.

Brewster was a son of Dr. William J. T. G. Brewster of Connecticut, a Union
surgeon who served in the Rio Grande Valley during the Civil War, and who
settled at Jackson Ranch south of Pharr. Dr. Brewster and Lina Helen Box
married Minerva and Louisa Singleterry, stepdaughters of Nathaniel Jackson.
Dr. Brewster was at one time schoolmaster in Hidalgo. He sold a large tract
of land to John Closner and William R. Sprague of Chapin Town site Company,
including the 1400 acre site of future Edinburg.

William ("Uncle Billy") Brewster located his ranch house about 100 yards
northeast of the cemetery. He was a peace officer and later jailer at the
County Jail in Edinburg. He donated Brewster School in San Manuel. He and
his wife Emilia Rodriguez Brewster (1873-1945) had six children: Mary (Mrs.
Manuel "Toncho" Brewster), Louis, Emily (Mrs. Fernando Balli), Minerva
(Mrs. Erasmo Velasco), Estela (Mrs. Amado J. Cavazos), and John.

According to family tradition, William R. Brewster made a gentleman's agreement
with his neighbor, Esteban Bravo (1854-1924) of the adjoining Bravo Ranch to
allow the Bravo family to continue to make interments in Brewster Cemetery.
The first burial was before 1912, that of a baby of David and Emma Box Bravo
(grave is unlocated). The cemetery is located on a high knoll where the
floodwaters of the Rio Grande did not reach it.

According to grandson Captain Erasmo Bravo of Hidalgo County Sheriff's
Department, Esteban Bravo bought 22 acres from the Cavazos and Balli families
and founded Bravo Ranch, which is northwest of Brewster Ranch. He came to
San Juan in 1910, where he owned a grocery store operated by two of his
seven sons.

Santa Ana Wildlife Refuge acquired the Brewster Ranch property in 1978, and
the Brewster family retains the right to bury family members in the cemetery.