SCOM 2012 R2 add/update/remove Subscriber for Subscription using PowerShell

I'm trying to figure out how to create a PowerShell script that will change the Subscriber of a Notification Subscription. I've run across posts that explain how to modify the email of a single subscriber and I've seen other posts that have you re-creating/cloning a subscription (see below for links to those posts), but those aren't what I'm looking for. I don't want to have to re-create the Notification Subscription every time someone runs the script to update who's on-call. Also, I don't want a generic Subscriber where only the email/sms/etc. gets updated.

There's got to be a way to do this, but I'm not sure how. The Cloning Notification Subscriptions link below has a part in the script that just uses .Add and .Update, but that's after the Subscription is created with the Subscribers using Add-SCOMNotificationSubscription. I'd like to know if there's a way to use the .Add and .Update (or whatever) to update the Subscriber of the Subscription without having to re-create it. Any help would be greatly appreciated.

Cloning Subscriptions