diff --git a/tools/create_childs.py b/tools/create_childs.py
index 09d002ec2..c9f8bc9af 100644
--- a/tools/create_childs.py
+++ b/tools/create_childs.py
@@ -3,9 +3,10 @@
 
 Options
 -------
-    -P|--parents=NAME:VALUE,... specify parent property pattern to match
-    -C|--childs=NAME:VALUE,...  specify child property list to assign
-    -N|--names=STRING           specify object naming convention
+    -P|--parents=NAME:VALUE,... specify parent property pattern to match (required)
+    -C|--childs=NAME:VALUE,...  specify child property list to assign (required)
+    -N|--names=STRING           specify object naming convention (default is '{class}_{name}')
+    -M|--modules=NAME,...       specify module names to use (defaults to those found)
 
 Description
 -----------
@@ -36,6 +37,8 @@
 import json
 import re
 import datetime
+import subprocess
+import random
 
 EXENAME = os.path.splitext(os.path.basename(sys.argv[0]))[0]
 
@@ -58,21 +61,58 @@ def error(msg,code=None):
     if type(code) is int:
         global EXITCODE
         EXITCODE = code
-    raise GldException(msg)
+    if DEBUG:
+        raise GldException(msg)
+    print("ERROR [create_childs]:",msg,file=sys.stderr)
+    exit(code)
+
+
+def load():
+
+    if not INPUTFILE.endswith(".json"):
+        tmpfile = "."
+        while os.path.exists(tmpfile):
+            tmpfile = f"tmp{hex(random.randint(1e30,1e31))[2:]}.json"
+        try:
+            result = subprocess.run(["gridlabd","-C",INPUTFILE,"-o",tmpfile])
+            assert(result.returncode==0)
+            with open(tmpfile,"r") as fh:
+                model = json.load(fh)
+        except:
+            raise
+        finally:
+            os.remove(tmpfile)
+            pass
+    else:
+        with open(INPUTFILE,"r") as fh:
+            model = json.load(fh)
+    return model
+
+def save(fh):
+    print(f"// generated by '{' '.join(sys.argv)}' at {datetime.datetime.now()}",file=fh)
+    for name in MODULES:
+        print(f"module {name};",file=fh)
+    classname = CHILDS["class"]
+    for obj,data in OBJECTS.items():
+        print(f"object {classname} {{",file=fh)
+        for prop,value in data.items():
+            print(f"    {prop} \"{value}\";",file=fh)
+        print("}",file=fh)
 
 def main():
 
     PATTERN = {}
     for name,pattern in PARENTS.items():
         PATTERN[name] = re.compile(pattern)
-    OBJECTS = {}
+
     if "class" not in CHILDS:
         error("you must include a class name in the child properties",E_INVALID)
     classname = CHILDS["class"]
-
-    with open(INPUTFILE,"r") as fh:
-        model = json.load(fh)
+    model = load()
     assert(model['application']=='gridlabd')
+    global MODULES
+    if not MODULES:
+        MODULES = list(model['modules'])
 
     for obj,data in model['objects'].items():
         data['name'] = obj
@@ -88,13 +128,11 @@ def main():
                 if not prop in ["class"]:
                     OBJECTS[name][prop] = value.format(**data)
 
-    with open(OUTPUTFILE,"w") as fh:
-        print(f"// generated by '{' '.join(sys.argv)}' at {datetime.datetime.now()}",file=fh)
-        for obj,data in OBJECTS.items():
-            print(f"object {classname} {{",file=fh)
-            for prop,value in data.items():
-                print(f"    {prop} \"{value}\";",file=fh)
-            print("}",file=fh)
+    if OUTPUTFILE.endswith(".glm"):
+        with open(OUTPUTFILE,"w") as fh:
+            save(fh)
+    else:
+        error("invalid output file format")
 
     return E_OK
 
@@ -103,6 +141,8 @@ def main():
 PARENTS = None
 CHILDS = None
 NAMING = None
+OBJECTS = {}
+MODULES = []
 
 if __name__ == "__main__":
 
@@ -132,6 +172,8 @@ def main():
             CHILDS = dict([x.split(":") for x in value.split(",")])
         elif tag in ["-N","--names"]:
             NAMING = value
+        elif tag in ["-M","--modules"]:
+            MODULES = value.split(",")
         else:
             error(f"option '{arg}' is invalid",E_INVALID)