What do you think about adding a checkbox so the user can identify the primary registrant?
Looking at our test registrations the primary registrant as identified by EE is not necessarily the person doing the registration and paying. This is because a parent may register mulitple kids for a race distance higher up the list of ticket types than the distance they are entering. EE currently identifies the first registrant in list order as the primary registrant.
The function you shared above gets around the issue with Stripe getting the wrong email. Thank you! However, looking at the test registrants in the EE backend I see kids being marked as the primary and it would be great for our record keeping if we had the right primary registrant marked for each group registration.