If I claim my father-in-law as dependent with itemized return, if my Mother-in-law files married separately, does my she have to file itemized as well?

My in-laws are living with us, and Mother-in-law had some income making her not qualiti be our dependant, but father-in-law qualifies to be our dependant. I'm filing itemized and claiming my father-in-law. So now does my Mother-in-law have to file itemized because my father-in-law is as a dependant on an itemized return?