Linking Material Files (*.sldmat) with Company Excel File

Hi Everyone. I'm trying to link the Material File (*.sldmat) to one of our company's Excel files. As the *.sldmat files are in XML, I can map the fields, I can link to and read them in Excel, but it seems that editing the files can only be accomplished using a different tool (I use XML Notepad).

The screenshot below shows how I've successfully been able to edit the material files which propagate back to Solidworks:

however, when I attempt to do something similar in Excel and then save/export, I get this:

Again, as the company files are in Excel, using it (or Access) are really the only option.

Does anyone have any suggestions?

Many thanks.

SolidworksBill Of Materials