Not sure which product I need. Doing 4 returns, 1- student and medical, 2-medical and northern living allowance, 3-pension income splitting

With the online version of TurboTax, you pay per return and can elect to use a different edition of TurboTax for each return you prepare. Once you've signed into your account and start a new return, TurboTax will prompt you to choose an edition.

That being said, it sounds like our TurboTax Standard edition might be your best bet for all the scenarios you describe.