Family Search shows the marriage of Alexander Watson and Margaret Smith recorded at Alvah on 29th June 1782. It also shows two children: John, baptised 17th August 1782, and Elizabeth, born 10th, baptised 16th October 1784.
There is no monumental inscription to this family at Alvah. As there seems to be no record of further children, there is always the possibility that one or other of the parents died quite soon.
One point worth noting is that their first child, John, was very "premature". As the parents had obviously been "guilty of the sin and scandal of antenuptial fornication", the Alvah kirk session minutes will probably contain a reference to the couple which might give further genealogical information.
Presumably you have seen the actual entries from the marriage and baptismal register. What were the names of the witnesses to the two baptisms? These can be useful pointers to a previous generation.
