Unfortunately, we do not have a co-teacher option available. Sharing a login account is the only alternative as of now; we hope that can work for you. You will need to use the same email and password to login, so be sure that the information you're using is info you're comfortable sharing.
A co-teacher option is on our to-do list so keep an eye out in the future! We appreciate your patience on this -- we are a small but hard-working team, building all things teachers tell us one at a time :)