Hi heather - Alva Stirling and Alva Clackmannanshire are one and the same except they kep the records in either place..difficult I know..bin there done that...
What I have is (and not my line)
Children of George Drysdale and Catherine Duncan Davie are..and not in chronological order.
Mary Ann 12/3/46 Alva.
Robert 13/9/47 Alva.
John 14/11/49 Alva
Catherine Smith 21/11/53
George 1854 Alva.
Isabella 1860 Alva ?
1861 census they are at Johnston St Alva and Catherine is listed as proprietor of houses ??
Catherine's birthplace is given as Causbiss sic ?? Stirling.
So we have Robert 1848, John 1850, George 1854, Catherine 1852 and Isabella ??1860..John Blcakwood Lodge and Agnes Harrower servant.
So this looks like your lot.
Robert Drysdale and Catherine Smith married 11 Feb 1799 Alva.
Children..once again not in chronological order.
William 1811, Catherine 1801, Mary 1799, Elizabeth 1803, Robert 1816, James 1806, Margaret 1813, George 1808.
These according to IGI Although if I were you would try and confirm with SP.
Know Alva pretty well, but a long time since I was there last

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Afterthough - Hi Monica

All the best patvp and good hunting..let me know if I can help.