Campbell family - North Knapdale to Greenock to Bonhill/Alexandria to Glasgow

Looking for any links to Dugald Campbell and his wife (?) Mary Thomson (McTavish - gaelic). As far as I can tell they originated in the North Knapdale area (which has LOTS of Campbells, all with the same few forenames aaargh!!). First known offspring Angus Campbell b. 1814 North Knapdale (parish and census confirmed), then Alexander 1818 and Mary 1822 (census only, no parish records found) in Greenock. These three siblings are first found, minus parents in Bonhill/Alexandria, Dunbartonshire on 1841 census. Angus m. Margaret McGregor, Bonhill 1842. He died 1874 Alexandria. Alexander m. 1) Mary Stuart/Stewart (only wife with offspring) 1841 Bonhill; 2) Janie Watterson 1864 Glasgow; 3) Isabella Walker 1867 Bonhill. He died 1878 Alexandria. Mary had a child Mary 1841 to (stated on Mary's marriage record to James Kinloch) a Duncan McIntyre, seaman, possibly a relative of husband 2) Donald McCallum m. 1844 Bonhill offspring Margaret 1847; Duncan 1849; Dugald 1851 (none of these children in OPR - likely free/evangelist church). 3) probably a bidey in Thomas Burns - Agnes Burns b1862 Bonhill, Annie Burns b.1865. 1871 census Mary, Thomas Burns and sons Duncab and Dugald in Glasgow, Dalmarnock Road. Mary died Glasgow 1878.