iPad problems

Unless you also have an iPhone, your iPad cannot send or receive SMS or MMS messages to phone numbers - as these are Cellular Carrier features. Without an iPhone, your iPad is limited to sending/receiving messages via the Apple-proprietary Messages App.

Native iMessages are directed to Apple recipients by their registered email addresses - and not by their Cellular phone numbers. The Cellular number associated with your iPad’s Data-SIM is only used for account identification and billing purposes.

To use SMS/MMS messaging from the iPad Messages App, your iPhone must be logged-in to iCloud with the same AppleID - and message forwarding to your iPad must be enabled on the iPhone.

https://support.apple.com/en-gb/HT208386

I hope this is helpful in clarifying your iPads Messaging features.

SMS app can be used on an iPad (model with wifi+cellular) in conjunction to an iPhone, as per this support guide:--> How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac - Apple Support

But I still do not understand what do you mean for "update" your messages. Could you please better explain?

Regards

Giulio

What do you mean for "update my messages"? Update the SMS app? What else?

Thanks

Giulio