NHibernate version:2.2

I want to get the list based on two selection criteria.

First criteria is for class.

Second critera is for one-to-many collection list.

For Example

Class a
{

string name;
private IList<b> _List = new List<b>();
}

Class b
{
string name;
int id;
}

My method is GetList(string filedFilter,string listFilter).

Question: How can i get the list base on the above criteria