What exactly are you wanting to do? What are you trying to edit or add???
Default for satellites.xml is "etc/tuxbox"
IF you install the satellites.xml in "etc/enigma2", it will also work. The etc/tuxbox location is a system file location and is subject to updates. But if satellites.xml is installed in "etc/enigma2", then the receiver uses it and ignores satellites.xml in etc/tuxbox.
I think for what you are doing, etc/enigma2 is the best place to put the satellites.xml. If there are problems, simply remove the satellites.xml from etc/enigma2, reboot the box, and the satellites.xml in etc/tuxbox will be used.