2nd Securing for the Mushroom

[brainbug007]

Has anyone got any pictures of how they did the 2nd securing for the mushroom? I can't really do anything elegant like some have on here using a lathe or tig welding an extra bit on. I'm guessing I need to drill a hole through the upright and mushroom somewhere but would love to see where/how some other people did this before I attempt it!