If it were my software I would want to know if it's an "option" or a "work-around" and also look at what the standard is and find out why that feature is not standard in your software. There were many instances I needed to switch carriers on a claim by claim basis! the only work around I can see for a software that doesn't allow this is to delete one carrier, add the other and re-add it later on ..but that surely isn't productive or efficient.