[Storebror]

I did take out your UP link as UP links are not allowed here at this site.

Never mind :wink:
I can't say I didn't know it...

is there ownership of things
Made for IL2 by modders or is there not

The simple answer would be: Yes, if the author claims to and has his rights asserted.
For instance you could seal your mod by a proprietary software license.
In case of a new aircraft this could, for instance, use the DiffFM mod whilst prohibiting reverse engineering by the included license. Since the classfiles of your A/C are compiled, the FM/DM is encoded in a separate file and the meshes are type of "compiled" as well, it would break your license if someone would touch your A/C in either way and you'd be entitled to sue him in that case.
Following common sense I'd rather say some kind of "No" - it should be a matter of ethical principles not to alter someone else's work without asking him/her for permission, but after all the contributed work should be disclosed for modifications if neccessary. Further more I personally wouldn't mind if some work of mine would become part of someone else's "pack" as long as sources remain mentioned correctly.

Best regards - Mike