A handy feature of iOS is the ability to forward SMS messages from your iPhone to your iPad using the Continuity feature, even if the sender isn’t using an iOS device. There may be times when your phone is charging (or hiding) in another room and a text message comes in. With message forwarding enabled, you’ll receive a notification on your iPad whenever you’re sent a text message, which you can then read and respond to directly from the iPad Messages app.
To set this up, open the Settings app on your iPhone and scroll down until you see the Messages icon. Tap the icon and then tap on Text Message Forwarding
Click the switch for the name of your iPad to the On position. If you wish to forward text messages to your Mac, flip the switch next to your Mac’s name.
A pop-up message box will display on your iPhone, prompting you to enter in an authorization code. When the code pops-up your iPad, type it into the the text box on your iPhone and then tap Allow.
Any text messages that are sent to your iPhone will now automatically be forward to your iPad (and to your Mac, if you’ve enabled it).