Joyelle Brandt is a Canadian relational trauma survivor who is coauthor of the book "Parenting with PTSD" and offers free newsletter (https://parentingwithptsd.wordpress.com/).
There is no free online support group at this link.
There is a newsletter. When you sign up for it you get the first month free.
OK, that's a change - there used to be a group. The newsletter is free though, it's just they give you the first chapter of the book when you sign up. Tks for posting BC, I'll adjust the post to reflect this.