Although I haven't contributed to this thread I would like to congratulate Isobel for her stirling efforts and determination to unravel the facts of this mystery, and also those who have added additional valuable facts. It is a long and at times confusing thread, and there are probably some loose ends still to tidy up.
I think it is good to consider that just because someone, or their descendants, holds a position of power in the community that they may not have skeletons in the cupboard, as appears to be the case here.
Having said that, Gordon is being painted as a bit of a fibber and a wife deserter, which may be unjustified. A bit more speculation, but it may be that Gordon went ahead to Australia to settle before sending for his family - it often happened that families travelled to the colonies separately - but his wife may have decided she did not want to make the journey?
We will probably never know. Well done to all researchers.