If you ever want to make an email (or any Aero) Related (so that they point to each other) to another Aero after they have both already been created, you can do that. It just involves a little bit of a hack.
- Open the Aero you want to attach the email to in Edit mode
- Scroll down to the bottom of the page and click the Show More button
- Look for the field called Related Aero. You're going to paste a number in there.
- In another tab, open the Email you want to attach by Reading it or open it in edit mode
- In the browser bar, look for the number (it can be from 1 to 6 digits) that comes after the words "DoTask" "ReadEmail" "AttendAppointment" or "Edit". Highlight and copy that number.
- Go back to the first tab and paste the number in that Related Aero field.
- When you next are working on that Aero, you will see the Related Aero tab with the email in it.