Multiple choice with Mobile Workers as choices

Hi guys

Looking around for how to populate a advances multiple choice question with the mobile workers under the current project space. What's the instance name/Syntax for the lookup table?

I found the documentation about having the organization's location/hierarchy as choices, so ideally, the mobile workers that would show up in that list would be the workers whose current location was selected.

Pointing me in the right direction would be greatly appreciated

Mazz