I claimed the tuition fee for my son, but forgot to mention in his return. though we did not claim in his return and the summary also does not show it. what should i do?

If his return has already been filed, you'll need to make an adjustment. Here's how: https://turbotax.community.intuit.ca/replies/2647992

If his return hasn't been filed, here's how to enter in his return that a transfer is being made: https://turbotax.community.intuit.ca/replies/2648072