Dynamic template and fields: FieldsetTab inside FieldsetTab

[vmo]

Hi,
I need to create a script to create a template and the template fields using data from a CSV file using the template and fields API:
- The template will have more then 600 fields;
- The fields are going to be organized using different FieldsetTabs fields;
- There will be FieldsetTabs fileds inside FieldsetTabs.

I saw some posts with examples how to create a template and fields using the API
but looking to the API I can not figure out what is the correct order to do the steps to create the template and fields and how to organize them into FieldsetTab.

What I understand but I am not sure:
1. Create a template
2. Create all FieldsetTabs
3. Create all needed fields
4. Create a Fieldgroup
5. Add all fields to the Fieldgroup
6. Add the Fieldgroup to the template

There are any example how to create FieldsetTabs inside FieldsetTabs and fields inside that FieldsetTabs?

Thank you