Money In The Meantime

My husband was just named the executor on his father’s Will. We all knew that he would be but the death was so untimely that it was not worked out beforehand. Now it seems like the only brother is going to be battling us for the long haul on this one and he even wanted to be joint executors. Finally it is settled that my husband is the sole executor and now the real work begins. My question is what do we do about money in the meantime before this case is settled. I am sure that the probate attorney is not going to just accept an I.O.U. for his work.