Mother-In-Law

I am the matron of honor for my friend`s wedding in June. My friend has decided to have two bridal showers because of the amont of people and costs of one. The bridal party would have one with friends and some family, while the mother-in-law will have the one for the majority of her family. The mother-in-law feels this is completely inapproriate. She has a guest list of approximately 40-50 people that my friend doesn`t even really know. The bride has a list of about 30 people she actually wants at her shower. If 75% of the people invited are from the mother-in-law, then shouldn`t she contribute more to the bridal shower?