It sounds like we'd need an apex trigger. I can get this done in a couple of hours, I'd have to look into the requirement in detail to confirm.
I'm a Salesforce developer with a background in web development. I previously worked at a Salesforce ISV building banking applications, presently I work with non-profits building on the Salesforce for Non-Profits pack.
Let me know a good time to start off. I work during CDT hours, so it will be easy to connect.
Best,
Allen