I am filing tax returns for my wife and child (first time). Do they need to register their own CRA login or can I use mine? Can I request their NOA through my account?

[TurboTaxSusan]

If your child is filing for the first time, they won't be able to create a CRA login until they get the NOA for their first return. They can't use your account because CRA MyAccount logins are one per taxpayer. Your account is tied to your SIN number and no one else's.