At long last, I can answer my own question - for anyone who's interested. The link, recently found, is the record of SSW's 2nd marriage - 16 Apr 1863, St Catharines - to Elizabeth Gould. It lists SSW's parents: "Peter & Elizabeth Weaver". So Peter (1786) and Elizabeth Van Every (1791) did have a 4th son - Samuel Seymour. Indeed brother Walter Weaver's obit says there were four brothers (and several unnamed sisters we'll probably never find). Anyway, the link for SSW to Peter was sufficient for UELAC, and I'm now officially descended from Francis Weaver, United Empire Loyalist (Peter's father). Thanks for everyone's help over these 11 years! Bob