My grandmother died and left about 400 dollars in the bank. She has no legal heirs. We wanted to split the?

money between her grandkids with the permission of my grandmothers children (our parents). Here is the hard part. Before she died, she found out that there was a mistake made on her birthday certificate, her real name and birthdate are different from the name and birthday she's been going by all these years...ssn is the same... Since her death the bank will not give us the money in the account because of the name/birthday discrepancy even though we presented all the doentation that all but points out directly that these two people are in fact the same person. Now they are saying (the bank) we need something called a small estate affadavit but after a visit to the court house this is a form they do not have. They say we need a lawyer but all that sounds like it's going to cost more than the money in the bank but I hate the fact that the government will eventually get her money. Is there anything we can do. Or does the bank/government get to keep the last of the money?