Yeah, site specific relaxin injections, taken for short periods of time (no more than 3 months?)...
I've been asking my sister about this for a while, and i did get her to admit that there could be a way to make it beneficial.
Could be really good for muscles that have tightened up due to injury?
In my case, i think the root of it is a tight lower back... can touch my palms to the ground and then some, so hamstrings are fine, but something stops proper pelvic tilt from occuring to allow for great sideways leg flexibility.
I'd love to see something like this developed to help my on my quest.