Complex sentence: Until the 1941 stroke that incapacitated her, she lived on the third floor of the White House and continued to manage Roosevelt's daily business, also presiding as the White House hostess during Eleanor's absences.
Split into simpler sentences: Until the 1941 stroke that incapacitated her, she lived on the third floor of the White House and continued to manage Roosevelt's daily business. She also presided as the White House hostess during Eleanor's absences.