Critical Alerts on IPhone

My wife and I both have the Ring App on our iPhones. Notifications go to both phone OK if for example a door is opened and closed, ring doorbell rings, etc. But we had the alarm go off while we were away and the critical alert went right to my iphone lock screen but my wife's Iphone did not get the critical alert. I have checked everything I can think of on her phone to make sure critical alerts are enabled. Can critical alerts only go to one iPhone? Any suggestions to get critical alerts going to both iPhones? Thanks