I haven't come across any connection to a Sarah Cairns but thats not to say there isn't one. I guess from the date of Sarah N birth Sarah Cairns would have been born in the latter part of the 19th or the beginning of the 20th Centuary and this is not a period in time that I have covered in any great depth during my research. As to to Andrew Nisbet. I have no record of Rev William N having a son of that name. His children were, David, Catherine, Janet R, Arthur G. On the night of the 1861 Census his Nieces Isabella & Margaret Graham were visiting from Fenwick in Ayrshire.