Sharan Newman is one of these authors. I 'found' her at book 5, and bought the next three installments as they came out. By the time The Outcast Dove (the 9th in the series) was published, the big boxes were in trouble and I eventually stumbled across my copy in the Daedalus catalog. It's been a while since I spent any time in Catherine LeVendeur's 12th Century France, and in that time, I'd lost track of some of the family relationships. Catherine's father Hubert was Jewish and forcibly converted as a child, one of his brothers escaped and eventually became his trading partner, and a third brother voluntarily converted and became a monk after disowning his son Solomon who eventually went into his uncles' business, taking over Hubert's partnership when the older man returns to his Jewish faith.
The Outcast Dove is a solo outing for Solomon, although he encounters both his father and Hubert, as well as a knight named Jehan who was once engaged to his cousin's sister. Luckily, the plot does not hinge on knowing the relationships between the characters because if it did, I would have been totally lost. While on a secret mission to free a family friend's fiancee who'd been kidnapped and forced into prostitution, Solomon must also discover who murdered another friend's prospective son-in-law and guard an unbalanced woman another associate is returning to her family. That may sound like a bit too much plot, but Newman ties the three lines - and a personal matter of Solomon's - quite neatly. The killer is a surprise, but fully supported by the preceding 300 pages, and most of the characters have a happy ending. I enjoyed The Outcast Dove, but I think I would have enjoyed it more if I'd read it either with no knowledge of the rest of the series or without a 5+ year gap since the last installment.