Is it permissible to fast to expiate an oath along with the six days of Shawwal?

Some jurists have stated that fasting six days of Shawwal with the intention of making up missed fasts (qada'), fulfilling a vow (nadhr), or expiating an oath (kaffarat al-yamin) earns the reward of fasting the six days of Shawwal, even if the reward is not complete. This is the apparent view. However, it is better to intend each fast separately to obtain the full reward.