If I keep my Ramadhaan qadha fasts during the month of Shawwaal, may I include in my niyyat the 6 Sunnat fasts as well?

Answer

It is not valid. According to the Hadith, fasting Ramadhaan plus the six days of Shawwaal is the equivalent of fasting one year, that is 36 X 10 = 360. This is minus qadha which is a portion of Ramadhan. The view stated in Shaami, according to our Akaabir is erroneous.

Concurrent observance is valid where the objective is attained, e.g. on entering the Musjid one performs the Sunnats of Zuhr or Asr or Tahyatul Wudhu along with the niyyat of Tahyatul Musjid. This combination will be valid.