I have Newlands relatives who lived in Ratho about the time you mention. I'm not sure if they are related, but am doing more research. I checked the 1881 census for your Robert Newlands, and it appears he was still unmarried and living as a boarder at 3 North Street, Barony, Lanark. He was a stone dresser to trade. According to the Family Search site,there were also a lot more brothers and sisters born to Thomas and Margaret Borthwick.