I have 4 samsung devices at home. Every time I add one of them to my SmartThings home, the app tells me “You need to reset your device to add it to SmartThings. All settings information in the device will be deleted.” If I continue, the new device gets added, but my other devices gets removed from my account, making me add It again. This has essentially made it impossible to have more then two devices added to my home at once, which is obviously not intended. How do i get multiple devices added to my home so i don’t need a lengthy process everytime i want to access them.
The title of the thread says SmartThings is making you reset your app but the message you quote is asking you to make sure you have reset the device that you are about to add.
What are the devices you are adding and what exactly are the actions that you are taking in the app?
Came here to say this too. 
“Resetting” your device in this context is putting it into pairing mode, and should not affect existing devices, or the app.