Hi @elchinaslanli,
So you’re aware, we’re planning for BlueOS to be both re-skinnable and extensible in future without needing to create a custom fork of it, which should allow for easy customisations while still maintaining the standard upgrade process, without relying on a fork author to pull updates downstream and host their own core images. Once those features are fully enabled the hope is that custom forks will not be necessary (since they fragment the code and user-base), and where possible we intend to work with interested developers to ensure the BlueOS architecture and system meets their needs.
If there are particular aspects you’re interested in being able to change, please let us know so we can take them into account as we flesh out the extension system, and/or so we can work together to make your desired changes possible 
Assuming you want to use your own fork in the meantime, your install script is still downloading bluerobotics docker images, which means it’s running our BlueOS containers. Running your own would require building your own docker images from the code, putting them on docker hub, and pointing the links to the new ones instead of ours.