Is it permissible to combine the intention of expiatory fasting for two consecutive months with the intention of fasting Ashura, Mondays and Thursdays, and the White Days?

There is no impediment to combining the fast of expiation with the fast of Ashura, Mondays and Thursdays, and the White Days. This is because the intention of the Lawgiver is fulfilled thereby, and the fasting person receives both rewards. The فقهاء (jurists) have stipulated the permissibility of this, among them Sheikh Muhammad ibn Salih Al-Uthaymeen, who mentioned that whoever intends to fast the day of Ashura, or Arafah, or the White Days, or Mondays and Thursdays, with the intention of making up for Ramadan (definition), it is hoped that he will receive the reward for the make-up fast and the reward for these days. Similarly, Ibn Hajar Al-Haytami, in "Tuhfat al-Minhaj," issued a fatwa (definition) that whoever fasts a make-up fast or a vowed fast in Shawwal or on the day of Ashura will receive the reward of their supererogatory counterpart, but will not receive the full reward associated with the intended act.