How can I add another input to a control and simulation subsystem?

[Laura121]

I tried adding it manually by dragging the wire to the subsystem, but it does not connect. See attached picture for clarification of the situation.

[Zach-H · Accepted solution]

Inputs and Outputs of a SubSytem work similarly to a SubVI.

You'll need to open the subsystem, add a control to the Front Panel, and wire that control to the connector pane. 

The process for a subVI is pretty well documented here.