Mark, I hope we're on the same pg, and following the same family.I don't know what VA census you're referring to, but Thos R & Anna M WILLIAMSON are in 1910-20 Allegheny PA census.Thos either d or div, as Anna is now m to Harry C IRWIN/IRVIN 1930. The info Cullen provided is good.
According to St Louis MO birth records, Maude is not Anna's middle name.Frank is her twin, and she is listed/indexed as Minna....can't tell if the "a" is part of the name, or an initial..b 6-25-1881. Anna & Thos m 1901, but haven't found marriage yet. Very few online PA records.
Thomas Ritchie WILLIAMSON b 8-2-1880 tall/med build; blue eyes/br hair Sec/Treasurer Home Beneficial Assn...WWI Draft Reg.
Thos R "WILLIAMS" 19 VA b 8-80; Ins Agent, 1900 Allegheny PA
8-3-1935 Virginia K WILLIAMSON m. Jacob S BROOKS, Allegheny PA [Anna's marriage was not listed]
1940 Dormant, Allegheny Co PA Harry & Anna IRWIN, Virginia BROOKS [widow] are living with Anna's dau & husband Dorothy & Judson FOSTER.