You will likely need to contact a Telus Representative directly to learn what options might be available n older plans.
See the Contact Us section into page footer.
I tried to add a new device today and was told that I couldn't add devices to my Peace of Mind Connect plan any longer since the plans were no longer available for new customers. I made a post about it here...it's a bait & switch.
You should still able to add a tablet or connected device to the plan. They would just have to use promo code: POMC-ACCESS when adding it. Not sure about other provinces but I know in SK it’s listed at the bottom of the rate plan brochures for existing Peace of Mind Connect customers.