Presumably you have seen Robert and Mabel on the IGI with these children?
James b 4 Mar 1779 NBL
George b 9 Jun 1781 d 12 Aug 1848
Eleanor b 16 Apr 1784
Robert b 10 Mar 1788
John b 4 Nov 1789 d Jan 1831
Ann 19 Jul 1792 d 1860
A second entry has Robert christened 27 Apr 1788 at Wylam, with mother's name Mable.
A third entry has Robert senior b 1753, and marrying Mable 17 May 1778
Another entry has a Robert b 1783 to same parents.
Yet another entry has Robert born abt 1785
There are possible descendants but you will need to know where Robert lived and preferably his wife's name to be sure you find the correct family.
There is also a very interesting Ancestral file for a Robert Stephenson born 1753 with previus generations using STEPHENSON STINSON.
Jan