tarsharwok

I'm hoping that you can help me track down a book I read approximately 20-30 years ago. I believe it was in pb format. I would describe it as historical (?Regency? Edwardian -definitely not modern) romance/fantasy. A young girl with magical powers is orphaned and sent by her grandfather (I think.) to become the ward of a very learned, powerful man who might have been a mage/sorcerer/very learned scientist. I believe she arrived by horse drawn carriage. I remember a grand house; yet, not a castle. I think that several boys around the girl's age also lived with them and that there were elements of humor involved. I don't recall any particular elements of danger; more the idea of the man teaching the girl to handle her gifts and how they eventually fall in love.
I have tried Booksleuth on AbeBooks, tried Googling and have written to the Library of Congress (They acknowledged receipt of my enquiry, but never responded beyond that.) as well as to the New York Public Library. I have corresponded with Lynn Kurland (who suggested posting on GOODREADS, which I did.) and Jill Barnett. I know it is not a book by Teresa Medeiros.
I truly remember loving this book and would really like to track down a copy