ANSWER:

Fasting 2 consecutive months is only for expiation for having intercourse while fasting during the daytime of Ramadan

If a woman is required to fast for two consecutive months, and she starts fasting when her period comes, that does not break the continuity of her fasts. She should stop fasting, then after she sees her purity, she must perform ghusul and resume her fasting immediately to complete the two months, because menstruation is something that Allaah has decreed for the daughters of Adam, and she has no control over it. This is something on which the scholars are agreed. 

https://islamqa.info/en/answers/82394/she-got-her-period-whilst-fasting-for-two-consecutive-months-does-that-interrupt-that-continuous-fasting

QUESTION: I have been fasting for 2 consecutive months for expiation.  I’m confused on how to make up the fasts for when I have my period during this time. I expect to start my 7-day period on day 55. When my period finishes, how many days should I fast to complete the expiation?