New phone, can't use Smartthings app

I created our Smartthings account using a new Samsung account for my wife and I, using our joint email account. I installed the Smartthings app to my old S7 using that account and it worked fine.

Now I have an S9 and I tried installing the Smartthings app but haven’t had any luck. The app won’t let me use a different Samsung account than my phone is set up with.

Is there any way to sign into the Smartthings app with a different Samsung account than my main phone account?

This was discussed in detail awhile back but no, you can only be signed into one Samsung account at a time on your device. You could add your main Samsung account as another user for Smartthings…

My old Galaxy S5 behaves the same way so it’s not just your new device.