I'm working a form at the moment and was consider merging sign in and sign up but thought it might be confusing. Is there any precedent for this?
This has been asked before but the answer was more about the word selection and pointed to this article which I thought was a bit off the point.
Or alternatively, what if the button was dynamic i.e. if the email address was recognised they'd see a button saying 'Log in' but if it wasn't then it would say 'Sign Up':