@AKG Good day,

To control 1 camera on 2 cell phones, both phones should login to the same tp-link account. 

For example if the Kasa camera has bound with your tp-link account, on your husband's phone, please login with your tp-link account  ( same email address & password)  and camera will show up on a second phone  . Note do not need to add or run set up camera again on the second phone. 

Activity need cloud service to work. Unlike KC110,  KC115 does not have free cloud service so there is no activity for KC115,for details, please check this realted thread: 

https://community.tp-link.com/en/smart-home/forum/topic/260892