Interesting to think that Flora's husband was RT Justin.
I have read fan theories ages ago that Naomi was a Collins by birth and that she and Joshua were distant cousins. Isn't there some hints that Naomi was a Collins by birth, such as saying the Old House had always been in her name?
That leads into the theory that Flora was Naomi's blood niece, and thus also a Collins by birth. I've always liked that theory, connecting Naomi and Flora as close relatives, and Flora a blood relation to Daniel and his offspring. Flora and her husband, whoever he was, would then be distant cousins.
I've also heard it suggested that the McG name was Flora's late husband's name, and after his death she and Desmond took on her maiden name.