Guest And Bridal Shower

I am giving a bridal shower for my niece and would like to invite a few relatives that will not be invited to the wedding. Is this appropriate since I am giving the shower. I realize that my niece wants to keep the wedding guest to a certain number. I do know that these guests would love to just make contact at the shower even if they are not invited to the wedding. Is this the proper etiquette? Thanx, Francine Jack