Is WHMCS ready for what is becoming the norm in the EU for billing?

[FlorinMarian]

Hello, friends!
In order not to be too long, it is becoming normal throughout the European community to send invoices from WHMCS to the tax authorities in the country of residence.
For this, I discovered three big problems that I personally do not know how to approach to be as effective as possible, these being:
1. Is there a simple method to add required fields to the registration page? (Personal numerical code / Fiscal identification code)
2. For existing customers, is there any way to force them to fill in that new field if they want to continue using the existing services? (basically prevent them from paying their bills if they haven't filled out that previously mentioned field)
3. Is there a simple way to export invoices in XML format according to the European invoicing standard? (SN 16931)

Thank you!

[WhmTools]

I guess we have to develop a whmca addon module for those cases.   What xml format do you want to export ? Is there a document for that  ?