[bjowen]

Okay, you’re using that word in an unconventional sense. In your usage, the US Congress would be an “offshoot” of the British Crown. Movements that stand in opposition to a prior established manner of thought are usually referred to as something like a backlash or a reaction or a breakaway.

[jahewson]

Thank you. “Breakaway” would have been a better choice, yes. In that the lineage is there but they are incompatible.