integration with other products

Very frustrating to me that if someone is already on another list, they don't get added to a new list through my various app integrations.  Kind of defeats the purpose because if someone is in my funnel and they finally become a member, or register for something, they don't get added to my list (i.e. through moonclerk and brilliant directories) so I have to do it manually. Also, I was told this was fixed and it wasn't.  Does anyone have any work arounds???