As larrabee said, your child is not an additional applicant, but you still have to mention them on the form and answer questions about them (plus I believe you still need to include their passport, birth certificate and evidence of where they live).
For accommodation, they want to know what your housing situation is as a couple.
So, they are asking:
Do you and your spouse live in a property that you and/or your spouse own, or do you and/or your spouse rent that property? Or, if neither, what is your and your spouse’s living situation.
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