It's understood that many people have shared without an issue. However, many people have been denied and the guests without a SDP were charged the full cost.
When the question comes up on the forum, it's best to make it clear that sharing or transferring a meal package is not allowed. If the server allows it or looks the other way, that's fine but it shouldn't be expected to happen every time.
"SDPs are personal (per person, e.g., 2 guests cannot share 1 SDP meal) and non-transferable (guests cannot give their SDP meals to someone else). " - Terms & Conditions