I already answered your question above. If you go to the Canada revenue website and search for schedule 1 and look at the line numbers, it will tell you what you want to know. The same thing with BC428 or any other province you happen to be in. The automatic default to the person with the highest income, usually needs the deduction more. There is no point in wasting the deduction on someone who has not paid much income tax.
If you don't understand how income tax rolls out, take it to a preparer. Errors cost you money in errors and penalties.
