I concur with your research into Margaret and Esau Harris and Jane Brain.
Susannah is my 3* Great Gran via her daughter Letitia who was born only 3 months after Susannah married John Ruck. So I am still wondering if Letitia's father was John Brain or John Ruck; we will probably never find out.

I note your previous message about Letitia's husband Edmund Fletcher's will. It was unusual for a 'poor' collier to have a will. So you may be interested to know that a family member has told me that Edmund's son-in-law George Nelmes (Sarah's husband) was approached by a Mr Jones (maybe the witness to Edmund's will?) about forming a joint venture to purchase a small mine in Pillowell; I don't think it ever happened though! But it does seem as though they had managed to save some cash.

Perhaps this is too speculative to put on the Forum!

Whitecroft1946