Hi,
the main thing that affects the scheduler in SCRUM is to my experience the Ranking information. (there are other ways to modify scheuling, but for the above purpouse I would use ranking)
So I would link the dependent WI with Depends On/Blocks to document the dependency, and then use the ranking in the plan to make sure that the blocking workitem is always ranked higher then the blocked workitem

This gives some basic control.
What this does not solve is the behaviour of the scheduler,if the two items are assigned to different owners. then the scheduler will still assume that both workitems can be scheduled in parallel instead of on after the other..

Still, if you work in rather short sprints,the dependency management should be possible by the team internally and fr the backlog,the ranking will be a sufficient mean to make sure you do things in the right order IMHO.

I think as well, it would be a great improvement, if the scheduler would somehow respect the Depends On/Blocks relationship.