Here are some of the OG characters, plus a few new faces for the next-gen stories. There will be other characters, but I'll list/introduce them when the story they appear in is published.
The Fletcher-Courtenay Family
Sera's parents
(fraternal twins, i.e. non-identical)
Martha is Sera's paternal half-sister, while Samuel is also Daniel's brother
Martha & Sam's children
The Whitaker Family
a.k.a The Duke & Duchess of Kendall (yes, seriously)
Also, Sophie is Sera's aunt
Lady Léa & Lady Éliane (for real)
a.k.a the Earl of Castleton (just kidding... ha, no, actually I'm being serious)
The Rousseau Family
Emma is Sera's aunt
The Delaney Family
Lucas is Sera's uncle; he and Milli have been together for almost 30 years but never married
not twins
The Taylor Family
Michael, a.k.a Mick, is Isaac's BFF and Sera's god-father
Maxwell is Lyanna's (adopted) son and Martha's friend
Isabella Casek is Michael's half-sister (this is where I will tart to lose you all)
Who the F is Annabelle? Surprise! Michael & Lyanna had a 2nd baby - Hi, Annie!
The Saylor Family
James is Martha's BFF (and huge movie star)
The Leahy Family
Keira is a cousin of the Delaney family but we know her as Martha's BFF