Childcare Flexible working

When I check with HR for TCS flexible working hour for Newly parents. HR responded that pls share medical documents. My baby is born little early in just 8 months. And my wife is struggling to care alone.she barly need my support & presence to take care my baby. So please advise what kind of documents hr looking for. Or suggest what type of wife medical condition will be shown to avail benefits of the flexible working arrangement. My case is genuine.