The only curse that is on the former members of the Partridge Family cast is the same one that many celebrities suffer from. Many die young, while others make bad life choices and end up addicted to drugs or alcohol. Although the untimely death of Suzanne Crough is sad, it's not an indication that there is a specific curse on the Partridge Family.
Just because Suzanne Crough has died at age 52 does not mean there is a curse on The Partridge Family. Every one dies eventually, and some die earlier than others for many reasons. We should not assume there is a curse, because curses do not exist and we should not live in fear.
I do not believe that there is a curse on The Partridge Family cast. People die all of the time especially when they reach a certain age. Maybe it was just her time to go since it happened so suddenly. There also was not a current cause of death at the time.
No, I believe that show business places undue stress on the people who work in it. For child stars especially, the stress in early life leads to complications later on. Many actors and actresses die young because of drug use, hard living, or even suicide. It is not because of a curse that the actors in The Partridge Family have died young.