Hi Everyone,
Yes David, your clusters within communities occur regularly - I suspect even today! Oh and Robyn has similar thoughts too.
Here's my latest "tuppence worth" - watch the variations in the spelling on these TWO 1810 marriages at Parramatta NSW, each recorded twice, yet NO record found in the Col Secretary's records for either of these brides

(These marriages are indexed online at NSW BDM)
At Line 1103 of volume 3A there's Daniel Kelly marrying Catharine Carr
and then
At Line 455 of Volume 147A there's Daniel Kelly marrying Cathrine Car
Sometime later in that same year
At Line 1149 of volume 3A, there's Joseph McKenley marrying Catharine Clemens.
At Line 466 of Volume 147A, there's Joseph McKinley marrying Catherine Clemens.
NB Vol 3A commenced back in 1788 and seems to include marriages conducted at Norfolk Island (ECR shown as CG on NSW BDM records are recorded in that volume., remembering marriages in those times were according to the rites of the Established Church - C of E)
David, I do not have access to your Hainsworth book, sorry.
I tend to favour the CLEMENS surname as a possible nee name for Catharine Christina Mcnally.
Need to obtain more Tim Tams, so catchyalata
Cheers,
JM