I am really sorry to ear that you are stuck using Cuety, I cannot create fixtures file for fixtures using subfixtures but i can give you a trciky way to make it work. In your case this fixture would request 21 fixtures to be able to work!
You need to create a fixture for your main part controlling dimmer and strobe. Then you can use a 1ch dimmer fixture from the generic library, you need to patch 10 of them.Then from the same generic library patch 10 units of the RGB fixture.
so as said, it will take 21 fixtures to patch only one unit...
I am sorry i cannot help you any more,
Good luck!
