Using Variables In Transformation

Would it be possible to use a variable to select these fields in a data reader property? see attached 
I have several replicas of the same database same schema and the built a transformation to a staging database.  I will be performing the same exact transformation on each so instead of building, lets say I have 7 copies, I build one and in a package, I just pass data reader variables to select the server, the database, and loop through all copies and extract the data? If you need me to draw a diagram I could if my explanation  isn't clear enough.  Thank you 

Sorry, we missed this question.

The recommended approach would be to use global variables.

Here is a very basic example

www.etl-tools.com/wiki/knowledgebase/tip...lopment-environment/

Global variables are used when you design the transformations so you can actually see the data and test the transformations

Then within the package you overwrite the global variable value using "Set variable" package action

www.etl-tools.com/wiki/advanced-etl-proc...et-variables-action/

It is also possible to store list of values in the database and loop over it