It is not valid to combine making up missed Ramadan fasts with fasting six days of Shawwal with one intention

Can You Fast the Day after `Eid Al-Fitr?

She did not fast because she was pregnant and breast-feeding, and she did not make up the missed fasts until she got old and became unable to make them up, then she died. Can fasts be done on her behalf?

She fasts on Mondays and Thursdays with the intention that if she owes any outstanding Ramadan fasts then these are to make up for them, otherwise they are naafil fasts

He thought that his fast had been spoiled, but he refrained from eating out of respect for the sanctity of the month, then it became clear that it had not been spoiled; does he have to make up that day?

She is not sure whether she formed the intention to make up a missed Ramadan fast before dawn or not, so she changed her intention to observing a voluntary fast

She did not fast because she was unaware that fasting was obligatory for her; does she have to make up the fasts?

If there is an error in the moon sighting, and it is proven that we did not fast on one day of Ramadan, do we have to make it up?

She was fasting to make up missed days, but she said: I am fasting six days of Shawwaal

What Happens If You Break Your Fast on Purpose