It's my guess at first they didn't plan on giving Pam a brother until they got halfway through the writing and forgot to go back and mention him. It would make sense that he was out with friends until just after dinner and then came back for curfew and then sneaked out again.
shareThis is definitely a flaw in the script. Up to the point where Greg has to go to Denny's room to borrow some clothes there wasn't a peep that the kid existed.
shareDenny was staying at a friends’ house for a few days, or was traveling. Problem solved.
shareTrue, but unless there's a good reason for a key character to remain a mystery until a particular moment, a well-written script will somehow inform the viewer that the person exists and not wait until the flick's half over. Otherwise, the viewer will naturally respond, "Who the fudge is he (or she)"?
The revelation about Denny so far into the story reflects sloppy writing, as if the creators were making it up as they went along (which is probably what happened with the character of Denny).
We’re talking about a silly, goofy comedy here, not Shakespeare. Heck, the uncle wasn’t mentioned earlier either, and we only discover him when he shows up at breakfast.
I don’t think the writers were overly concerned with how Denny fit into the timeline of the plot…..(and nor should we be), lol.