editing opengl32.dll

is it possible to edit an opengl32.dll ?
or does one need the source to edit it and than compile it?

Sure, you CAN edit it without the source. A good disassembler and strong knowledge in assembly, the system and what you want to do, would probably be a minimum requirement. The easiest way would be to change the original source and recompile it, but given that Windows is not an open source OS, you would have a hard time getting the source.

No you cannot realistically mess with this. It’s a compiled Microsoft windows component required for the correct operation of all OpenGL drivers on Windows.

Don’t mess around with it. It really requires source code and that is not available.

If you want to mess with OpenGL drivers then Look at Mesa, and maybe Linux and the DRI on that platform.