combine the quartus projects

When working with a team on the same FPGA I find it easier to do the top level file first. Create a project with all the pins, and that goes down to one hierarchy level with one box per sub project. Connect the boxes to the pins, define the interfaces between the boxes, and then distribute that "empty" project to everyone and have each one work on his part. Then it is a lot easier to merge everything back together, even during intermediary phases of the project to check that the subprojects work well together.