TurboTax incorrectly claimed my step son as an eligible dependant. My spouse, the kids mom and I became common law Jan 15. How do I fix this?

So, I can’t claim an eligible dependant as I’m not single or divorced. Now cra sent a review. I actually need to change my return and claim the amount for my spouse in schedule 5, 30300 instead of 30400 but I don’t know how.