Understand the case below: 

I have Odoo 15 instance with multi company option. I create Quotations, Sale Orders and invoices for a particular customer lets say "Mike" in "Company A". 

I grant "Mike" portal access. He can login and view his quotes, sale order and  invoices of "Company A".

Now I create invoice for Mike in "Company B". But non of the "company B" quotations, orders and invoices are visible on Mike's portal.

I want this to be visible in Odoo 15.

I'm able to do this in Odoo 16 by adding both the companies in "Allowed Companies" option in the User section. However this is not showing any result in Odoo15.

Will appreciate your help.