For Tasks
Go to the Gantt.
Click into "Add new column"
Add columns "Predecessors" and "Outside Predecessors"
(You could also add "Successors" / "Outside Successors")
Note: For Predecessors you will see the row number
For Outside Predecessors you will see the 'Project / Schedule / Task' Name.
For Schedules
Go to the Schedules List page
Look in the Predecessors column
This will show the row number of any schedule predecessors.
Note: If there is a chain icon on the right hand side you can hover the mouse over to see the Schedule Name(s).