Setting a primary service if one gets cancelled

Question

We have an app that allows the user to add multiple services. Example, as a user, I'm able to add multiple "Teachers" to a job that I've created. So essentially, these teachers will be working on one this one job that I created.

The first teachers will default as the "Primary" service.

Sometimes, we need to cancel a teacher if they are no longer able to make it to the job.

If there are only 2 teachers and the primary one gets cancelled, the 2nd teacher assumes primary status (because obviously, that's the only remaining one).

If there are 3 teachers though and the primary one gets cancelled, what's the best approach?

1. Disallow the user to cancel the primary teacher until they select a new primary teacher between the 2 remaining ones

2. Automatically assign primary to the teacher that was created next/soonest

Answer 1

Ask the user at the moment they're attempting to delete the existing primary which should be the new primary service.

Answer 2

Dont you have teachers rating. As ideally how can you assign a teacher primary status unless you know who is the best.

Having a rating will let the system choose on its own whom to assign primary status. But if that is missing, I guess the default should be random as then all teachers are equally likely.