Deleting using nhibernate

I have an organization class and a client class.  Before deleting an organization I want to check if an organization is tied to a client/clients, if this is true deleting the organization should not be allowed.  I just started learning nhibernated and was wondering how to go about checking if an org is tied to a client.

Thanks in advance,
Jane

you canc heck here to know more about the relationships in nhibernate
http://docs.jboss.org/hibernate/core/3.3/reference/en/html/example-parentchild.html
https://www.hibernate.org/hib_docs/nhibernate/html/example-parentchild.html