Can two parents use the same account?

There are two ways.

Share the login

Both parents can log in with the same email and password, each on their own phone. Your children's profiles come along on every device. See Sign in on a second device. The terms ask you to keep your password inside your family.

Invite the other parent

Each parent then uses their own email and password.

1. Open the Parent/Teacher area on the Profile tab and pass the phone check.
2. Pick the child, then go to "Students and invitations."
3. Tap Invite another parent.
4. Type the other parent's email and tap Send invite. The app says, "Invite sent! The other parent can use it to join."

The other parent gets an email. The invitation works for 7 days. See I got an email inviting me to join a family.

Plans

Only the person who bought a plan can change or cancel it. The app says, "Only the person who bought this plan can change it."