That's a lot of work. Almost anything can be done, but it is hard to determine the costs without seeing it first. Can you see the drain lines coming down into the basement from above? Can you tell where it exits the house? If you are lucky, it goes all the way down and dissapears in the floor. If so, then you may not need an ejector system (best to avoid unless necessary). All of the things will need vents. Basically, you may need to tie all of them together and then either make a new one to the roof, or patch into the existing one upstairs above the highest sink level. Depending on the size of that vent, you may need a new one on its own. You may want to install a separate water heater which, if gas will also need a flue. Lots of things to think about. The incoming water supply lines may be marginal for another apartment.