Problem1:
I have one filter already defined at the class level and wanted to have another filter at classs level. How to implement that?

Problem2:
My class structure is ClassA, ClassB and ClassC.

Class A contains set for Class B. They have one to many relationship.

ClassB and ClassC has many-to-one relationship. So I have following method call in my ClassB.
public ClassC getClassC(){//return instance of ClassC};

My initial filter in ClassA filters isactive='Y' column of Class B and works fine. This filter defined on the set collection of ClassB in Class A.

Now I have to define another filter at ClassA which filters
ClassB.ClassC.cityId =5 and it also need to implement at set collection of ClassB in ClassA.

How to do that?

Now I have just tried to implement single filter on a collection of ClassB at ClassA.

Where my condition is CITY_ID=:cityId where CITY_ID is a foreign key of ClassC. But I am not getting expected result.
Looks like filter is not working.

So what I am doing is
Class C has a many to one relationship with ClassB.
Class B is a collection on ClassA.

I am putting above mentioned filter condition in ClassA.