My mom, my husband and I are selling a home that all three of us own. My mother wants her down payment back, out of the seller proceeds. Entitled?

My mother, my husband, and I are selling a home that the three of us own. My mother chose to pay a $21,000 down payment on our FHA loan when we originally purchased the house. Now, she demands her original down payment out of the proceeds first, then she wishes to split the remainder with us fifty-fifty. Is she legally entitled to receive her down payment first? Is there a legal standard for seller proceed allocation when the parties don't agree?