Hi, unfortunately the software only allows for a user to enter a maximum of 2 vehicles for a particular return. You can still add a 3rd vehicle by printing and submitting a 3rd T777 with your return. If you want do want to NETFILE, you can file your return and then file an adjustment, details on how to do that can be found here: https://turbotax.community.intuit.ca/replies/2647992