Hi Andrew, I've found something I think will work for you in T17 (I'm unsure if it will work the same in T14) using only a single performance activity with notifications. Please let me know if this is on track: 

Create a new performance activity with the following configurations in instance creation:

1. Creation date is open-ended, date type is relative, frequency is repeating

2. Choose your reference date, in this case 'job assignment start date' and choose anniversary if users have existed for awhile before this activity

3. set your instance creation start date to be however earlier than your reference date

4. set a due date in reference to your start date (a bit odd you cannot reference your reference date here in my opinion).

5. Under content, choose whether the activity closure should be upon completion or on due date (if you're wanting reminders on the anniversary, then automatic closure on the due date might not work).

6. Then with notifications, you'll want to set up 'participant due date reminder' notifications relative to the due date that you want.

The gap with this approach to your use case is in having all instances created at one time during a period. However, with the above approach you can achieve work levelling, creating instances before a relative due date, and reminders on the due date (OK if activity is overdue, or, schedule the due date so that notifications occur on the reference date).