Two or more cell phones to arm and disarm

I set up my pro board about a year ago.  Used network cable.  Worked great until I added my wife's cell phone.  Now, whichever phone I use to arm, only that phone can disarm.  Both phones display everything and get alerts, but only the arming phone can disarm.  Did I make a log in mistake when I set up her phone?  Both phones are Samsungs and I used the pre-installed app.  I un-installed and re-installed apps in both phones, but still does this.