When adding my medical expenses, do I also add my dependants medical expenses? (Three children one of which disabled and lots of costs incurred).

[TurboTaxSusan]

Yes, you would enter the medical expenses of any dependants under 18. If any of your children are over 18, this TurboTax Canada FAQ shows you how to enter their medical expenses: How do I enter medical expenses for dependants aged 18 or over?