How to transfer a Pro level DPS account license from one publisher to another?

Here's our scenario.

Publisher A owns the Professional level DPS license.

Publisher A has split into two seperate companies - Publisher Company A and Publisher Company B.

Publisher Company A will no longer produce tablet editions and plans to transfer the DPS license over to new Publisher Company B.

How does Publisher Company A legally tranfer this DPS license?

Thanks in advance for any advice or roadmap.

Tom