Коменты в коде, или надежда умирает последней

  from p
  in pdb.Conversation // From all conversatiuons
     where
         p.user_ref.All(
         x => // Select those, who contains user names... At least I hope he will do that.
         (
         x.nt_user_id == userFrom
         ||
         x.nt_user_id == userTo
         )
         )
     select p; // Do!