Adding a dependency - one option
Creating links between schedules can be done in several ways. One way is by simply typing the link path in the predecessor column. Please make sure you refer to the correct line number in the other schedule (e.g.
If you are working on a Project Server you will see the name of the file, if you are working on a stand-alone version of MS Project you will also see your file's location on your computer.
At opening, the other schedule will see the ‘Link Between Projects’ window with the possibility to ‘accept’ the creation of the external link (click on the second line 'Delivery Parts B' in the Link Between Projects window > Accept > Close). When this edit to this schedule is saved, then the link is finalized.