TurboTax files each and every return separately, because that is what the CRA requires. There is no “Jointly-Filed” return in Canada, like there is in some other countries. TurboTax allows couples who are married or common law partners to prepare their returns together, so it is easier to do things like transfer credits, etc.
But if you want to prepare your returns separately, you can do that as well. TurboTax will ask you if you want to prepare together or not.
Last year my wife and I filed using 2 separate TurboTax files, is there a way I can merge these files so we only have 1 file for 2019?
Unfortunately, once you have completed your returns separately you can't merge them under the same one.
You can definitely start doing a joint/spousal return this year and then next season be able to have it all in one.
Remember when you are ready to file your return that you will need to click on your name and NetFile your return and once you have your NetFIle confirmation you will go back and click on your wife's name and NetFile hers then she will receive her confirmation number also.
Please note that NetFile doesn't open till February 24, 2020.
Here is a great FAQ to help you file as a couple - this one is for Online
Here is a great FAQ to help you if you are using CD/download version