Hi Bluesky,
Ho Hin is facing a similar problem, he has a Theater Musical Dance Performance at HKAPA on Jan 3rd, and his exam starts on Jan 4th, and won't finsh till Jan 14th; he also has competition in between. Not good timing at all. Hence, he spends few hours everyday preparing the exams during this X'Mas holidays. But, I still encourage him to participate both the competition and the musical dance performance.
Hope your son and Ho Hin can survive in their exams.
Cheers,
Andy