Margaret Macmillan or MCCOLL

My ancestors John Mcinnes and Margaret Macmillan or McColl married in June 1810 in Creich in the Ross of Mull (parish of Kilfinichen/Kilviceuen). I assume from the double surname that Margaret was a widow at the time of her marriage. I have, however, been unable to find any evidence of a marriage between a Margaret Macmillan and a McColl. Unfortunately "Familysearch.org" provides no easy way of discovering the identity of the unknown McColl. Can anyone help?

John and Margaret had five children: Donald (1811), John (1813, Findlay (1815), Mary (1818), and Janet (1821) and a number of grandchildren so hopefully there will be others seeking their ancestry who have hit this problem and solved it. If so, I would be delighted to have their help.

Douglas Mason