My husband (80 y.o.) has had a stroke and has dementia. I have become Caregiver, as well as am his spouse. I need help setting up his Apple Watch to connect to my phone (he doesn’t have one anymore).

My spouse has had a stroke (Aphasia) and also is experiencing cognitive decline. He’s 80 y.o.! Consequently, he can’t use computers, smart phones, or other electronic technology. I have shut down his iPhone line, but that leaves me unable to reach him with his Apple Watch. I have learned that his watch can be linked to my iPhone …..(I have an Apple Watch too) just as a parent can link their child’s watch to the parent’s phone…..However, I have no idea how to set this up. It is imperative that I can locate him if he doesn’t return home from walking the dog, or just taking a walk. I worry that he could fall and I wouldn’t know it. I am sometimes away from home for a few hours. I NEED TO BE ABLE TO REACH HIM OR KNOW IF SOMETHING IS WRONG. My phone carrier is COMCAST. They haven’t got a clue how to do this. Apple tech support is impossible to reach lately. Can someone help me? (I also have an Apple Watch Series 7)