Bulk invite guest users Azure AD - additional columns

Question

Hi,

We need to bulk invite guest users but we need lots of additional fields (like Job Title, Department etc.).

The template for Bulk Invite is very limited and when manually adding these additional columns the GUI says the CSV contains invalid headers.

How do we do this?

And also how to we bulk resend pending invitations?

I'm talking thousands of guests (for both initial invite and resend) so can't be done in any form of manual way!

Thanks