I'm currently trying to create an ISO-DE Layout in BootMapper but I can't see a solution, maybe somebody has more experince with it.
This is what BootMapper looks like after I plug in the PCB and press download (I only switched y and z): https://ibb.co/C5GDjjv
If I understood the tutorials correctly, I have to press one field of the matrix and then press one key of the keyboard below to change it, that also worked for switching y and z. But as the ISO-DE Layout has some special keys like ä, ö, ü or combinations of "',#", ".,:", I saw no way of adding them as I can only choose from the keys that are below (and they obviously don't have ä. ö, ü etc.). Is there a way to add them manually or am I screwed? 
Edit: Seems like I don't understand how key presses are sent to/processed by Windows, although BootMapper shows the UK Mapping, when I changed the Windows Language to German everything seems to work perfectly fine and ä, ö, ü are where I expect them. Can anybody explain/has a link, so I can understand what kind of signals are sent to the OS and how the OS interprets them?
