Customer Portal for Multi-Store Accounts

Customer Portal for Multi-Store Accounts

Hello, we have many customers that have more than 1 store.  Each store is an Account in Zoho CRM/Books. How do you handle this when your customer has for example 10 or 50 stores and their bookkeeper needs to log into the customer portal for orders, invoices, etc.  CRM allows for duplicate Contacts and email addresses, but Books does not. 

When a multi-store customer first logs into the customer portal for store 4 for example, they cannot log into any other store's account.  Now they can only see store 4.  

Surely the answer is not to tell them if you have 50 stores your bookkeeper has to create and manage 50 different email addresses, one for each store.  That's insane.  Is there a way to link the 50 Accounts together so when the bookkeeper logs in to the customer portal, they can then select any of their 50 stores to go to, like a drop-down list to select any of their related Accounts.

At one of the Zoho Zug meetings I attended, the instructor said this is done by setting up Branches which links the appropriate Accounts together, but then the other instructor said the Branches feature is only available in the India version of Zoho.  Zoho knows this need and solved it, but only if you do business in India?  What about the rest of the world?  We have multi-store accounts too and they all have bookkeepers too and they can't manage 50 different email addresses.

Has anyone else found a solution to this need to accommodate your multi-store accounts?