This is book number 4 in the The Baby-Sitters Club Graphix series.
Claudia and her sister, Janine, may as well be from two different planets. Claudia, who pays more attention to her artwork and The Baby-sitters Club than her homework, feels like she can't compete with her perfect sister. Janine studies nonstop, gets straight As, and even takes college-level courses! But when something unexpected happens to the most beloved person in their family, will the sisters be able to put aside their differences?