DT Max will automatically give the credit to the family head:
if you want the spouse to claim the credit in their file, use the keyword
Optimize and the option T1 - Claim the GST/HST credit on this tax return,
then select Claim under the keyword CONTROL;
you may also use the keyword GSTDependOV to enter the right
number of dependants;
The taxpayer claiming the GST credit must be 19 or older.