Karen,
John 1791 had a few siblings:
Charles b. 1793
Becca b.1795
William b 1798 (bap @ Corfe Castle 18.2.1798)
Charles b. 1800
Their parents were John (surprise surprise) and Elizabeth, or Betty.
I haven't yet linked this folks further back.
The information I have on John, who married Ellen is as follows:
Born in Knowle - Dorset - Tailor
Joined RA - posted to SA; christened in Langton Matravers 20/4/1824
That John also had a number of siblings:
George b.1818
Mary b.1821
Job b.1826
Elizabeth b.1831
I hope all this helps ?
Best wishes,
Paul
