Am interested in your Cathcarts. Am doing some research on Richardson Cathcart - son of James Cathcart and Elizabeth Lawrence. I think this Richardson emigrated to South Africa. I have a Richardson Cathcart marrying Mary Jane Cornwell. The Cornwells emigrated to the Cape from Rosecrea Co Tipperary.
I'm exploring the possibility that there is another connection between Elizabeth Lawrence and a family called Brown(e). I see from your posting that Elizabeth was a widow when she married James and I've found a note that her surname was Laurence/Brown. Three children from her first marriage - Brown, Alexander and Hugh also emigrated to South Africa (assisted passages. Hugh Lawrence married Mary Jane's aunt - Ellen Frances Cornwell. If I'm right about this connection, Brown, Alexander and Hugh were half brothers to Richardson.
Brown Lawrence and Richardson Cathcart made a great success of life at the Cape.