I didn't mention that one of my aunts (Aunt1), one of the people who confirmed that S2 did indeed receive $ from Dad (hence lied to me), insisted on getting involved. Aunt1 persistently said that she would talk to Dad to have him sort it out but I didn't want to get into it with her that night because she was drinking. I didn't want it to become an even more emotional conversation than it already was.
Anyway, I cc'ed her that email I sent to my sisters because I wanted her to back off and leave Dad out of it. Her son has been in recovery a couple years now (he's the cousin of mine who when to Caron) so she used some recovery language in talking to me about the situation such as "deep resentments are involved" etc.
I replied something about how I had established boundaries with my immediate family in 2012 and that is why I was compelled to set the record straight so that I was not to be maligned. This raised some very interesting recovery issues that I have been thinking a lot about lately. In particular, what is one person's boundary setting is another person's resentment harboring.