So I assume that your main line isn't tensioned. Correct?
That's correct. I posted this above:
Originally Posted by DannyBoy2k
I should also add that what I showed with rolling the Prusik won't work if the line you attach to is pulled taut. That would have the effect of unrolling the Prusik and unlocking it, which is actually the way I usually unlock the Prusik, by pulling both ends of the line it's attached to. However, this works great for a tarp setup where you are using independent lines for each side, not a single line setup, since one side of the line you attach to is slack. Also for tent guylines like the ones Opie sells.
A kite's bridle has enough slack that this works extremely well. It would not work on a completely taut line.