How should we count FMLA leave when both parents work for the same company?

Q. Our company employs a husband and his wife in different departments. Their daughter has been diagnosed with a serious medical condition that requires hospitalization for extended periods of time. The couple wants to know how much time they are entitled to under the FMLA to care for their child. Our company policy provides that spouses employed by the company can get only a combined total of 12 weeks to care for a sick child. Is that a correct application of the law, or does the FMLA prevent us from implementing such a policy?