ByDesign : Tax Decision Tree Localization

Dear Experts,

I am working with the localization and I got some questions about defining new Tax Type.

Since the country already have SAP Pre-delivered Tax (VAT) and we need to add another tax type,

Can we just create new Tax Type in PDI or we have to re-create all needed Tax Type (including VAT) and re-define all the tax decision tree for this country again?

If we can create only the one doesn't exist, How can I find the tax decision tree which is Pre-delivered by SAP in case we need to check or do some change?

Thank you very much for your response in advance.

Mullika.