Email invitations: application context in post-change-password event?

I want to use Send Email Invitations for Application Signup for a use-case in which there can be multiple pending invitations for the same email address: each invitation is associated with some state in our application that’s used to configure the user if that invitation is accepted.

We’d send an email containing a “change password” ticket url for each invitation. (/tickets/post-password-change API doesn’t suggest that you can only have 1 valid ticket per user.)

When one is actioned we’d use Post Change Password Trigger to notify our application that an invitation has been accepted.

I can’t however see any way to pass per-invitation state through this flow, eg by exposing the unique ticket url in the trigger event object.

Have I missed a way of achieving this?

(If this isn’t possible then we’ll have to simplify our invitation UX to prevent the creation of multiple invitations.)

(Apologies if this is tagged incorrectly, the UI didn’t allow me to select tags like “password-change” I can see in other community posts. I’ll try to fix once I’ve created the topic.)

– Richard