I'm fairly certain I should be able to do this but I can't seem to find out how. Basically I'm written a simple feature class merge tool in Python. It takes a series of input feature classes and a field name for each (the field represents a depth value). It then merges all of the feature classes into a single feature class with a depth field containing values from the field specified.
Writing the script wasn't hard, but I'm now trying to build the parameters for the script for a toolbox (note that this is a scripting tool, not a python toolbox tool). I need a multi value parameter that takes a feature class as an input and when one is selected it fills a combo box for a second input with all the field names for that feature class (or, for bonus points, just the numerical fields). But I can't find a way to set this up with the interface provided. I think the topo to raster tool in 3D analyst has an example of the sort of thing I want to.
I'm not certain if I can do this for a python script admittedly. I know I can do it in .NET but that is a different matter entirely.