If your parents choose to claim this amount on their tax return, they cannot claim it along with their own Medical Expenses. They must have you listed as a "Dependant" still, and the medical expense claim must exceed 3% of YOUR Net Income. This is called the "Medical Expense Tax Credit for Dependants Over 18", and more info can be found at this link: https://bit.ly/2OnqGtw

Here's how to claim this tax credit in TurboTax:

https://turbotax.community.intuit.ca/replies/2647799