Hi Portonian,
I have a few Ross's in my family tree, and as you know Cockenzie and Port Seton is full of Ross's, Buchanan's, Johnston(e)'s, Thomson's, Harkess's Donaldson's and Sinclairs.
I have a Christina Ross born 1882 (one of your Port Seton cousin's names) who married an Andrew Buchanan born 1880, he was my great uncle.
My grandfather, Thomas Buchanan born 1895, was born at Ross's Land, but not sure what or where it was. I thought it was a house down by High Street, owned by a Ross and rented out. My grandmother, was Margaret Grandison Ritchie, and that was another common name as well.
Will do some further research re Ross's Land etc.
Tom Buchanan