When is there a right to reimbursement for separate funds in probate?

My husband recently passed away. We were married 18 years. Before we were married, he had 25,000.00 in his savings account. While we were married, that money was deposited into another account which was in his name only, but community business funds were also deposited into that account. Community expenses were paid out of that account, and expenses for improvement to the community house were also paid. His family from a prior marriage are demanding reimbursement for the funds that he came into the marriage with. Do they have a right to those funds, or are they now considered commingled. The funds are no longer in the account as they were used during our marriage. All the funds along with monies earned during the marriage were used up over 10 years ago.