Move 400 PCs from one account to another

Hi, 

We use TV since v7 , we are actually in V13.

We have about 400 PCs in our TV account (we can called it tv1) and we recently merge with another compagny that have about 400 Pcs in another tv account (V13, named account2). 

All accounts are licenced.

Now that the compagny's support team is merged as well, we want them to be able to connect to the 800 PC on the same TV account 1.

What is the best method to merge all accounts in few steps,  in only one TV account (1), as we can't go physically to all 400 PC of account 2 , to unsusribe them and register them manually to the other account ? We used  Microsoft Windows GPO to deploy MSI with parameter files teamviewer.reg, and personalization in tv host filename. 

Thank you for you help !

Damien