Try adding him as friend with your 2nd account or so... Let's say his game is in the morning, you should check this out by trying to arange a friendly game, set up your league game almost 6hours after his game.. then hope you guys play in the evening
for example..
his game is at 11:00 am, you change your league game for 16:45
He can't play another game for next 3hours, that's 8:00-14:00(6hours B4&After)
You can't play a game between 13:45-19:45..(6hours B4&After)
This way your game would be in the evening..
Not sure if this would work but if you set up friendly games every 3hours or so and only leave free time in the evening ?
once the time for the final is fixed, simply cancel the friendly games.
Good luck for the final