title: join on list of objects with sub query of list of objects
body: <p>Would appreciate some help on this</p>
  
  <p>objects</p>
  
  <p>Vendor 
  string VendorID
  List VendorSets</p>
  
  <p>VendorSet
  string VendorSetID
  List VendorSetMembers</p>
  
  <p>VendorSetMember
  string VendorSetID
  string VendorID</p>
  
  <p>Using Linq  -- What I need is a way to get a list of all the VendorSets any vendor is in.  Not sure how to sub query the list of vendorsetmember for the matching vendorid and return the corresponding vendorset as a list of vendorsets in the vendor object</p>