A friendly warning about the novel Sylvester:

Heyer wrote her share of boilerplate, I'm Only Doing It For The Money books.
Sylvester is not one of them.
This is one of her more advanced, intricate, lengthy undertakings.

Sylvester must be read either in installments,
putting the book down and coming back when one has the time,
or by setting the equivalent of a long holiday weekend aside.

There are three full dramatic acts, if you like, in this novel.
Act One. The heroine escapes from her wicked stepmother.
Act Two. The heroine seeks refuge with her maternal grandmother.
Act Three. Sylvester's saintly mother rescues everybody from
the predicaments resulting from Act One and Act Two.

Hmmm. That sounds ... sarcastic. Sorry about that.
The sarcasm is unintentional.
The fact remains, this is one complex novel with a large cast.
You have been warned.