How to add non-GST invoices for leasing clients?

How to add non-GST invoices for leasing clients?

Hello Zoho team,
We use Zoho Books as our billing software. We are in vehicle retail business.
Some of our vehicles are sold on lease, where we add the leasing company name and address in the "Bill To" section and their GST number, while we add the lessee (client) name and address in the "Ship To" section when we create a new customer.
This is good when we sell the vehicle.
However, this creates an issue when we want to bill the client for any after-sales servicing, or purchase of auto parts. Here the leasing company does not come into picture. When we create an invoice for servicing of vehicle, it by-default uses the leasing company GST number which is not required.
How do we overcome this problem? We want to use the leasing company details only at the time of vehicle sale, but should not be using the leasing company details in any of the subsequent invoices for the customer.
We cannot change the customer details for subsequent invoices as this may update the existing invoices also, and we will not have any track record of the customer.