I have a multiple websites with CRM contact forms.

So when customer sends me a message it creates a Lead.

I can then convert this Lead to a Opportunity and with a built-in wizard assign to a new customer.

But I'm missing a website field - and by that I mean a website from which the Lead originated. This field is later used to assign portal users to this particular website.

How do I do this? I've seen similar functionality in module like this:

https://apps.odoo.com/apps/modules/12.0/crm_lead_vat/

In this module new VAT field is created and propagated to a new customer. But I'm not sure if I should modify it to use website as well or there are better ways?

Using Odoo13