Using more than a single layer as barriers in arcpy.TraceGeometricNetwork_management()

Question

I am working on script that iterates through trace flags and traces upstream. For each trace flag, I have selected features from multiple layers in the geometric network that I want to act as barriers to terminate the trace. I have tried merging all of the selected features in each iteration to a single feature class, but if there is not one and only one feature at each junction (we have some points that are disconnected and coincident with connected junctions) then sometimes the disconnected feature is flagged as the barrier and the trace does not end.

I have instead made a list of layers that have selected features as barriers.

list_of_layers =['lyr1','lyr2']
arcpy.TraceGeometricNetwork_management(geomNetwork, r"outNet",traceflag ,"TRACE_UPSTREAM", list_of_layers, "", "", "", "", "NO_TRACE_ENDS", "NO_TRACE_INDETERMINATE_FLOW", "", "", "AS_IS", "", "", "", "AS_IS")

but this fails

Runtime error 
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "c:\program files (x86)\arcgis\desktop10.7\arcpy\arcpy\management.py", line 6253, in TraceGeometricNetwork
    raise e
RuntimeError: Object: Error in executing tool

An earlier comment directed me to the tool help with states that this parameter is to be feature layer, not a list of barrier layers

How might one perform an upstream trace with barrier features selected on multiple point layer?

Answer 1

A work around:

I identified lines intersecting with my trace flag and lines intersecting with my trace barriers. I created mid-points at each of those lines and appended them to the trace flags and to the barriers, respectively, on each iteration. This DOES end up returning lines immediately downstream from the input flag, but for my purposes and with the way my data is set up this works for me.