Hello,
First of all, welcome to the Thor community! Thank you for your interest in the project and for wanting to carry it out for your students 🙂
Regarding the modification, I’m sorry I can’t help with this. I currently don’t have the free time to do any particular modifications.
I encourage you to do the modification on your own, after a few minutes you will see that using FreeCAD is quite simple and you will be able to do what you are looking for.
If you are not comfortable with FreeCAD, you can always use the STEP models, import them into Solidworks and modify them from there.
Best regards!