Like many BSC fans, I can’t stand Karen Brewer. I also started with the BSC books, so in total I probably owned about five. Mostly my mom would pretty much refuse to buy them for me because they were too easy, and why read the little sister when you’re already reading about the big sister? But there are lots of things in the BSC world that are mentioned–such as the death of Boo-Boo and Karen/Andrew moving to Chicago–that happen in the LS series and are only mentioned in passing in the BSC series. I always felt like if I weren’t going to put in the effort to collect all the LS books–which I will probably end up doing anyway–I should at least have the books that are most important in the LS series, those which have an effect on the BSC series and those which are just really amazing for snark value, whatever. So I asked the amazing BSC fans at my favorite BSC messageboard (I won’t link it cause I’m selfish like that and want to keep it small and nice) for their suggestions. Here’s the list they came up with.
Cat Stuff:
#103, Karen’s Movie Star: Boo-Boo dies. The Brewers already have Pumpkin, acquired in #102, Karen’s Black Cat.
Chicago Stuff:
#94, Karen’s Snow Princess; #95, Karen’s Promise; #96, Karen’s Big Move; #99, Karen’s Big City Mystery. In #94 Karen and Andrew learn about the Chicago move, in #95 Karen decides whether to stay or go, and in #96 she goes but can’t hack it. In #99 she visits them in Chicago.
Custody Changes:
#48, Karen’s Two Families; #49, Karen’s Stepmother. In #48 the custody changes and #49 deals with Karen torturing everyone in the big house for the first full month.
Random BSC Correlations:
SS#1, Karen’s Wish: Nannie breaks up her hip.
SS#3, Karen’s Mystery: Takes place during Snowbound. Goes into great detail about rat-napping.
SS#4, Karen, Hannie, and Nancy: The Three Musketeers: Parallels very to nicely with BSC at Shadow Lake. If you’ve always wanted to know more about the cottage, this is your book.
#6, Karen’s Little Sister: Deals with Karen’s reaction to Emily Michelle.
#12, Karen’s Ghost: Takes place during Mystery Admirer.
#15, Karen’s In Love: Deals with Karen and Ricky Torres’s relationship. This ties in with Logan vs Mary Anne where Karen is very mopey about the wedding being called off.
#19, Karen’s Good-bye: Amanda Delaney moves away.
#93, Karen’s Cooking Contest: We learn that Nannie’s name is Janet Taylor. Who knew that Nannie was a delinquent member of the Baby-sitters Agency??
Just Funny:
#8, Karen’s Haircut: Karen gets a mullet. Hannie says Karen is now too ugly to be a bridesmaid. The cover alone is worth the price of the book:

What other books do you guys think are essential LS titles? And big thanks again to all the posters at my favorite bsc board.
I remembered where the BSC references Bridgeport. It’s where Aunt Cecelia lived before she moved in with the Ramseys.