FMLA Question

Looking for any thoughts or advice- especially if you have experience with this type of situation.

I spoke with my supervisor in January about the time I would be out for FMLA after the baby comes. I told her I would be out March 7th- May 31st and asked if there were any specific tasks that needed to be done before that time. Last week Wednesday (a week before I am to go on leave) she tells everyone on the team that we have to have our documentation for the year together by April 1st. Since we have been asked to document all year but have not been given a format for organizing the documentation, it is going to take time to get everything together. However tomorrow is my last day until the end of May and I will not be able to complete the task by the end of day. Can they require me to work on this while I am out for FMLA since it was a task given before I left? Or am I justified in telling them I completed everything that was shared with me in my meeting with my supervisor and the notice was too short for this task so I will work on it when I return?