Hi
MarkSchofer -
Are you referring to instances meaning different urls?
For example:
http://qat1.test.comhttp://qat2.test.comAnd in what location are you trying to switch these? For example are you trying to have generic object references in your object repository? If so you can wildcard the portion of the URL that is changing.
If you are looking to alter this for different test runs navigation to the sites I would suggest using a variable to drive the URL you are navigating to. This way you can make the modification in one place at the variable.
Let me know if you have further questions.
Cheers,
Emma