When working with many bones, it is important to be able to have a shortcut or button that allows you to invert the selected bones, it would be very helpful.
Request Button "invert the selected bones"
What you want is already available in Spine, but you have to set a hotkey for it:
In the hotkeys file find: Select - Descendant Bones: and specify your preferred key combination. this way you will just need to click on the parent bone to select all of the desired children.
https://esotericsoftware.com/spine-settings#Hotkeys
There are also these that could help you speed up the selection process:
Select - Child Bones:
Select - Descendant Bones:
Select - Colored Bones: Thanks Erika