How do I add another phone to my icloud account

JudyLynnThompson wrote:

My husband could not find his iphone. I logged into my icloud account to "Find My Phone". There were four phones listed. One was my phone and the other three phones were listed as inactive. I could not add my husband's phone to my icloud and search for his phone. We finally found his phone, but it would have been easier if I could added his phone number and made his phone beep.

This is done in the Find My Friends app.

https://support.apple.com/en-ca/HT201493

I'm not following your question. On another device, simply login in to it with your Apple ID & password when prompted on the appropriate screen on setup.