Is it permissible to combine the intention of making up for missed Ramadan fasts with fasting six days of Shawwal, and what is the ruling concerning the days I fasted with the intention of combining them?

The ruling on this issue was previously discussed in Fatwa no. 33027, which states that if one combines the intention of making up (a missed fast) with the intention of a supererogatory (nafl) fast, scholars differ on whether this fast counts as a make-up or a supererogatory one. Therefore, it is obligatory to specify the intention for the obligatory fast and confine it to that alone, so that one's duty is discharged. This is the more cautious and preferable approach.