Once someone is represented by an attorney, each letter goes to attorney's address UNLESS attorney would provide both addreses-yours and attorney's. If USCIS would have addresses of both-yours and attorney's, then they would send the letter to both places/parties.
Though I know that your main reason to hire an attorney is-so that your attorney could receive mails from USCIS for you in your absence, but I must warn you to be very careful in choosing the attorney. Because, mostly cases in immigration are messed up because of the mistakes of attorneys. Most of them are so busy that they don't even remember a hearing/interview date of their client. Sometimes some attorneys purposely ignore an interview date so that their client could get in more big problem, which will produce a new job for attorney to make more money from their clients. But that doesn't mean that there are no good attorneys out there. That's why I said that make sure to get a good one.
Good Luck.