How to get, use and update Local Variables on the fly at keyword script?

How can I get, use and update variables locally defined by a Test Case in my keyword script (on the fly)?

In other words: How can I refer the Test Case which called the keyword, then get the locall variables of this Test Case, change their values and persist them?

I found out some topics at the forum about the use of Global Variables at keyword scripts, but nothing related to local variables.

Additionally, how can I create Test Objects on the fly at keyword script and persist them?