Best knot for hanging a swing from a tree limb? I used a bowline tied with paracord to hang a swing from one of my trees for my toddler son.  After a few days of use, it appears to be damaging the bark.  

I'm looking for a knot or lashing to hang a swing from a somewhat horizontal tree branch that has a loop so i can hook the swing into and won't damage my tree.

Ok with complicated knots.  Just want the right one for the job.