Though Sandi seems to be jealous of Quinn, many fans probably wonder why Sandi let Quinn into the Fashion Club in the first place?
My theory along with alot of people is this:
Sandi saw Quinn as a threat to their status as queen bee of Lawndale High, and so she invited Quinn into the Fashion Club in order to "control her" so that she would not be more popular than Sandi, however due to Quinn personality and craftiness it somewhat backfired and the whole Quinn vs Sandi saga in the Fashion Club began.
Anyone care to elaborate
