Approaching the sixth anniversary of the death of her husband, the 6th Earl of Dunmore, we find the widow and her three daughters at Bowhill House, Selkirk, the Borders home of the Duke of Buccleuch and Queensbury.
The RCAHMS entry may be seen here: http://canmore.rcahms.gov.uk/en/site/54280/details/bowhill/
The census records Catherine Murray, 36, Susan Murray, 13, Constance Murray, 12, and Alexandrina Murray, 5 and it may be presumed that these were the names that the girls preferred to be known by in private.
I have found a Charles A Murray, 11, Boarder, at Tweed Green Grammar School in Peebles which is within 25 miles of Bowhill House and about 50 miles from Dunmore Park. His birthplace is given as East India which is a cause for doubt as the 7th Earl's birth was registered at St George, Hanover Square.
It may well not be him but, on the other hand, it could be.