You can claim the deduction for the family. You may also qualify for the Additional Residency Amount, which is the same dollar amount as the basic residency amount, effectively doubling the amount of the deduction. To qualify for the additional amount, you must be the only person in your dwelling who is claiming the NRD. Depending on your spouse and children’s situation, it may be more advantageous to claim the additional amount rather than have two or more people claim the basic residency amount.
https://turbotax.intuit.ca/tips/understanding-the-northern-residents-deduction-5478