I'm not sure that you give away a GGL Redemption to someone else. My understanding is that the GGL member has to travel on any GGL Redemption Reward booking (but that it can include up to 4 additional passengers).
I understand the same as I tried to do something similar a couple of years ago where I wanted to use the joker for my family members when I was travelling on the same flight on a paid business ticket and the computer said no - but as an exception, because I was travelling on the same flight, the GGL team was able to make it happen.