As a mom or dad, how would you handle your preschool's negative attitude toward his younger sibling?

I would like to recommend a book on siblings relationship which I find it is very helpful in managing siblings conflicts. Sibling Without Rivalry http://www.amazon.com/Siblings-Without-Rivalry-Children-Together/dp/0393342212 The most important take away point is never compare your kids. The book gives a lot of scenarios on how to handle different conflicts between siblings. Also, for myself, I find spending quality time with each kid helps to reduce attention seeking behaviour from kids. Every week, I will devote a day specially for no.1 and no.2 respectively. We go out for a short date such as ice-cream day, library visit, movie day, and etc.