If you are trying to transfer tuition from your grandchild, you would need to enter them as a dependant (even if they are adults who take care of themselves) in order to do so.
Please see these TurboTax Canada FAQ for more info on how to transfer tuition in TurboTax:
How do I claim my tuition fees?
How do I transfer my unused tuition credits to someone else?
How do I enter tuition transferred from my spouse/partner or child
How much of my child's or spouse's unused tuition credits can be transferred to me?
