I'm building an interface for a client to add and remove email lists to their website such that visitors logged into the site see lists and can manage subscriptions to them. Say ... subscribe to three newsletters, and later unsubscribe from one but not all of them.
Add and remove is working, as is auto-populating new lists with the custom fields the site needs.
I need to be able to set the new list settings so that unsubscribing removes them from that one but not all lists.
Is this possible?
Yes - you choose the list you want them removed from in the API call Subscriber.Unsubscribe.
As long as the list is not set to 'add to suppression' they'll only disappear off one list AFAIK.