How to link Sales Orders field to Invoices

Hi,

I use Zoho to save Orders from clients and to create invoices. I configured a new field in the Sales Orders section named "number". This field is very useful to write the orders numbers sent by the clients. I would like to display this field in the Invoices section.

So, do you know how to link a field filled in the Sales Orders section to the Invoices section ?

In fact, I want to see this number in my Invoices section when I convert a sales order to invoice.

Thanks in advance.

Regards,
Brice.