I am trying to claim my fiancee as an eligible dependant for my 2017 taxes but it does not appear on the list. what option do i select?

[TurboTax-Terry]

You can not claim a "Spouse" as Eligible Dependent. You may be able to claim a spouse for the spousal or common-law partner amount provided their net income is below $11,653 for the entire year. You will need to indicate that your marital status has changed in 2017 to common-law and that you meet the CRA guidelines for this declaration.

https://www.canada.ca/en/revenue-agency/services/child-family-benefits/update-your-marital-status-ca...

Be aware that advising CRA of a change in marital status can have an impact on previously received amounts such as GST and Child Tax Benefits.