Do you need a solution with or without manual intervention? If you are ok with manual intervention and If you know when they will be checking in on the house you can setup a virtual presence sensor for family members. But this would require you manually enabling and disabling it when you know they will be there. I do this along with a virtual switch and SmartTiles dashboard when we have a babysitter in the house and we leave.
If you need an automated solution than it’s difficult to get away with not having to provide them some device that triggers presence detection. If the reason you don’t want to set them up with mobile presences is because of setting up ST Mobile on there phone you can always look into setting them up with Life360 accounts and you can track their geo location to your home without installing the ST app and giving them view of your ST config.
If presence is completely out and you just need away for them to arm and disarm you can give them a key fob or setup a keypad (iris has one that works with ST) CentraLite Keypads