Thinking clearly when using DFDM and thinking clearly when asking a question about it aren't the same thing. I was trying to figure out why I was getting a message why the files that I was looking for didn't exist. BigLouie and TomTarget are both knowledgeable and helpful, and I always appreciate their insights.

An invoice can disappear from the Open Invoice table after it is paid.

I wasn't getting a table at all. I got the message that the table itself didn't exist.

Melinda, you have me really nervous mucking around in DFDM based on your comments. I would really suggest talking with your Sage Partner if you really want to continue down this path.

Tom, I haven't been "mucking about"--I was looking around and trying to figure out where things are located, which should do no harm. I have used DFDM before when an invoice was mistakenly marked "paid" due to a cash receipt glitch, with the help and blessing of my reseller, but that was over a year ago. I was trying to remember how I did it and where I found the information, and don't need to invoke my reseller at this point, but will if and when I have to. If you're inferring that I'm recklessly changing data through DFDM, then you're mistaken.

"Can I easily change the date on an updated invoice?"
The answer to this is "no", and I guess the main consideration at this point is "why would you want to"?
If the numbers being in the wrong buckets bother you, a CM with the originally bad date, and DM with the good date would be greatly preferred to DFDM. First, it is easier (as well as being more accurate / complete), and second it creates an audit trail of the correction.

The only reason to change would be if it was an issue for accounting/profit statements. I wasn't even necessarily looking to do it through DFDM, unless it was easily done and didn't make a bigger mess (as stated in my original comment) because I know that it's best used sparingly and with the correct knowledge. I am marking your reply as an answer so I don't continue to get comments from people who think I'm leaving a swath of destruction in DFDM.

Invoice date would affect AR / sales type reports, but GL based reports only consider the posting date. If you use a sales based report for something important (like salesperson commissions), then doing manual calculations would be easier than finding out how that data is stored in the system and correcting it.