You have two choices - have two subjects or have two business contexts.
For the easy approach (assuming you don't really need separation, just a different source), just add the Inactive Subscribers table in your current data model and put it in your current information map as a new subject. That would also require a new contact history table in your CDM (like CI_CONTACT_HISTORY_INACT), and would allow you to use your current configuration but choose on a node-by-node basis whether you want to work with Active Subscribers or Inactive Subscribers.
If you want them fully separate (entirely different sets of data, separate users, separate storage areas for campaigns, separate CDM reporting tables & history tables), then the answer would to create a second business context. That means you'll need a new information map, new libraries (for your customer data, CDM and MATables), a new root folder in your Metadata, new user groups (probably), and then a new business context to pull it all together.
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