We cannot integrate with any of the available online payment providers as none of them are supported in our country.

What I thought to do is use provide the users a link to a third-party code that would use WildApricot APIs to retrieve and update invoice information and that would integrate with our payment providers.

The link would need to include some information about what the user is trying to pay and the most natural thing would be to include the invoice id or event registration id in the link query parameters so that the third-party code can use the WA APIs to get the amounts to be paid and also later update those invoices.

To my surprise I saw that the invoice id macro is not available in the event pending email neither is the event registration id.

So I thought ok let me try the invoice page itself (financial document system page). No invoice id there either!

The invoice id macro is only available in the invoice email but we do not send out invoice emails.

It would make sense to at least have the invoice id in the financial document page or even the event registration id in the event registration pending email (it has all the other event registration details but not the event registration id).