Joe, you shouldn't need to amend the parts XML for this unless you have hardwired a context giving a list.
The material context should work fine..
In the AeccPartParamCfg.xml file where the context descriptions are:
<AeccDfParameter name="Mat" desc="Material" context="Material_Type" index="0" datatype="String" usage="String_General" managelist="True" unit="" visible="True" internal="True"/>
The Managelist saves a list of used entries to AeccSharedPropertyLists.xml. If you want to add new materials do that here either by typing the new material in the parts material section or manually adding to the file.
You can always edit the OTB parts and do what you like with them, although it's better to create a backup in case you do something wrong. When you say it is saving a copy, I would check the admin rights to make sure you can edit these..
The way the paths work, all files the Xml, JPG and DWG should have the same name. If not it will not find them or use the correct file. You can change the JPG path / name in the XML (line 6).
If you have hard wired and are trying to amend the info but it's not holding it sounds like a link is messed up.
To test, open the corresponding xml file and go to the list section you want to add to. copy the last line in the list then paste below. Change ID="i#" to the next number in sequence and the value then save.
<ColumnConstList desc="Frame Height" dataType="float" unit="mm" name="SFH" id="CCL3" visible="1" context="StructFrameHeight" index="0">
<Item id="i0">150.0000</Item>
<Item id="i1">100.0000</Item>
<Item id="i1">100.0000</Item>
</ColumnConstList>
Rebuild & revalidate the catalogue, look for errors then try to change the properties to see if it has taken hold.
Review the validation file in \validate for the part to see where it is actually looking for this item, it will give the name in the last line.
Mike Evans
Civil3D 2022 English
Windows 7 Professional 64-bit
Intel(R) Core(TM) i7-3820 CPU @ 3.60GHz (8 CPUs), ~4.0GHz With 32768MB RAM, AMD FirePro V4900, Dedicated Memory: 984 MB, Shared Memory: 814 MB