How to reference a JSON parameter inside another JSON parameter?

Thanks, Michael, for the suggestion. That explains why what I was trying does not work. I am having trouble getting your proposed solution to work as well. It looks like the $node notation you recommend in step 2 is deprecated (Understanding the Differences Between $node and $() Expressions in n8n), and that is giving me a syntax error that I have not been able to resolve. I’ll keep working on variations to see if I can figure out the correct syntax.