If you need a variable in your data flow you can copy it and paste it in the relevant location in the data flow.
Procedure
Activate the Variables and constants bar.
Activate the Variables tab.
Select a variable catalog.
In the data flow, right-click the variable you want to copy, and select Copy.
Right-click at the position in the background of the data flow where you want to place the copied variable.
A Paste icon appears. Click in the data flow background.
You have copied a variable.
Tip
You can select a variable in the data flow and press Ctrl + C. Then, press Ctrl + V and place the copied variable at the relevant position.