The person who initiated me was as direct disciple of a biological descendent of Lahiri Mahasay who lives a short distance from their family home. I was introduced to him by a friend who had also been initiated by him. I don’t remember his name now though.
The spine is a metaphor for the body and the body is a metaphor for the universe. First the body is purified, then the spine. But that’s all about the self trying to untangle itself. There’s nothing that needs to be untangled. It’s all exactly how it’s supposed to be.