In the writers' first draft script of "Dear Doctor", Phlox's offspring were established as all being fully grown (as of the episode's setting, in 2151) and Phlox himself stated, "I'm quite proud of how most of them turned out."
Phlox's fifth grandmother prepared the same recipe for each of his weddings. He mentioned this to T'Pol when he had some in 2154, explaining that Chef tried to make it, but could never get it quite right. (ENT: "Doctor's Orders")
Having lived through the last war, one of Phlox's grandmothers still harbored prejudice against the Antarans, to the point of forbidding Phlox to visit an arboreal planet near their star system with some friends. Because Antarans had once lived there, she believed it to be unclean years later.
Phlox remembered laying in bed as a child, thinking about her stories, and having nightmares, afraid of an Antaran climbing into his window.
When he grew up, he never told his children her stories, opting for the truth over propaganda. He was proud to say that all of his children save one son, Mettus, considered her beliefs to be outdated.
In 2152, Phlox related this story to Hudak, in the hopes that the Antaran would accept medical treatment from him (ENT: "The Breach")
This character was only mentioned in dialogue.
This grandmother and the one above may be the same individual.
Along with Phlox, his spouses were each married to two other men each, who were, in turn married to Feezal and other women. One of Phlox's wives lived in the same town as his eldest son. (ENT: "A Night in Sickbay")
These Denobulans were only mentioned in dialogue.
In the writers' first draft script of "Dear Doctor", Phlox was referred to as having two wives, each of whom had three husbands. Evidently, this later changed to Phlox's wives ultimately being established as instead having two husbands each.