Buying a mr6400 as backup for my starlink Internet. Would like to receive sms or email alert when the connection changes to 4G so I dont run out of data. Have seen multiple of these request for archer

I have a starlink router, in bridge mode to my tp link M4. Déco is doing all dhcp work. Ik want to add the 4G router in-between, so it will act as backup for the starlink when it fails. Can I add it a