How to call existing RestAPI test from TestComplete Keyword Test?

How can we call an existing RestAPI call from a TestComplete Keyword Test?

I know we can use the "Send Request" in Keyword Test, but then I have to manually type all the input.

How can I say call ReadyAPI to run the "XYZ.xml ", a HTTP GET request with XYZ variables as HTTP body? 

Another requirement is run the RestAPI first, a Get HTTP request return some data, then use those data as variables to call a Keyword Test in TestComplete

I am trying to figure out how to integrate both TestComplete and ReadyAPI together, from one to call another.

Thank you for your advice. 🙂