
Hi Maysea,
I would separate the youngster well before anyone is leaving if that's the case - it's really not fair on your old dog :( and it sounds like it's becoming a habit which of course needs breaking before she gets any bigger/heavier.
Ideally you should be trying to prevent the older dog from doing this too (could you try distraction, or having a bag of treats handy for when visitors get up to leave so they could offer her a tit-bit?)
Even when kept apart the pup will hear what's going on and you'll end up with two noisy dogs

so it would be best I think to tackle both problems - but separately.
Just some early morning thoughts on the first dose of caffeine - really need another three mugs first :P - you probably need a B/M expert or a Lindsay :D
Regards, Teri