Hello,
beside the treats here...
there is no really good way to take over the leader rights from another player.
We decided to get this done by the GO team - so any GO can easly change the leader of an alliance in 3 clicks (and some key presses^^)
so, create a ingame ticket (tell me your universe here, we have in gen3 just 1 GO, that i can may look into this by myself)
regards
Dschibait