Where any parish or burgh shall be situated in more than one county, the Board shall, on application being made to them by any person having interest, determine in which one of such counties such parish or burgh shall be held to be situated for the purposes of this Act, whose decision shall be final; and the jurisdiction and powers of magistrates, justices, and sheriffs, and the powers of their officers under this Act, shall be regulated accordingly, and the Board may from time to time recall or vary such determination.