I too have heard the same thing about only being able to get the same amount of meals as your cards states and if am getting more than my card says my DM and I usually order separately, just in case. However, the few times when I have bought more meals than I have people on my card I haven't had a problem. I've now used
DDP 5 times, Sept. will be 6th.
Usually on our last day we use our leftover CS (or QS) credits to buy meals for the rest of our last day as well as food for the plane. First time I did this I asked told the cashier we would be ringing them up separately. (Max of 3 each time) she asked me why and I told her. She said she could do them all at once. This was at the food court of one of the deluxe resorts. So the next year when we went there again, I didn't even bother to separate the order.
The one time this came up at TS (my Dniece had joined us mid-trip and wasn't on the DDP) we were eating at Boma so everyone had to pay. I asked the server if he could do one of the meals separately. He asked why and I told him. He said it wasn't a problem, as along as I had enough credits left he could do it all on one. He even asked me who told him I needed to do it.

For the rest of our TS meals we ordered 3A and 1K meals each time (as per our card) and shared them between the 4A and 1K.
If you are worried they might say something, then have do 2 orders for 3 each. Some cashiers are more strict than others.