Win 10 Lock Screen, I want to add an app to it but...

Overall I like Win 10. Its smooth and fast and can only get better.

I want to add an app that shows the current moon phase on my lock screen. There are only two that I found an I cannot seem to add them to the lock screen via the 'add to lock' screen screen. I downloaded one and it works I as such but on start up on the lock screen is where I want it. 

Does anyone know of an app that shows the current phase of the moon that is able to be show on the Windows 10 lock screen?

Thanks