Instead, copy the core to a new folder, change it's name in the core.txt file, and have yourself a custom core all to yourself.
1. copied "arduino" core to "my_arduino"
2. changed "name" in /my_arduino/core.txt to name=my_arduino
3. selected "my_arduino" core in Hardware->Cores drop down menu..
PS: if the name in the core.txt does not match the folder name, the uecide freezes at the welcome banner, and it must be killed with the task manager's help..