Hugh,
Although your question is directed at Officers,this may assist
From the History of the 8th Royal Scots a Pioneer Battalion
November/December 1915:Various Companies of the 17th Northumberland Fusiliers were attached to the Battalion for instruction.
January 1916:The 1/6th Scottish Rifles were attached to the Battalion for instruction.
I should also add the obvious when mentioning the 8th Royal Scots

Prior to embarkation to France in 1914 a draft of 1/8th Highland Light Infantry was attached to the 8th Royal Scots to bring the Battalion up to War strength.In particular Lt J. Martin 1/8th H.L.I..It was Lt. Martin who Corporal W. Angus V.C.(8th H.L.I. attached 8th Royal Scots)) recovered from No Man's Land on the 12th June 1915 under enemy fire.
Lt. Martin was still attached to the 8th Royal Scots on 14/1/1916 when he was awarded the M.C.
George