Our wedding is in less than four week's and my FH's family are just NOT getting it. They are used to very informal family gatherings, and don't understand our wedding invitations.

Our wedding:
--is SMALL, so we are asking folk to leave children at home (so we can afford to have more friends attend)
--has a website, which explains our gift registry, directions to the site, dress code, etc.
All this information is explained (NICELY) on the invites and in the many, many emails we've sent out.

BUT... my future in-laws are being hopeless.

My husband-to-be's family--mostly cousins--will not send their RSVPs (they already have stamps on them!!), but insist that they are all coming. They are also insisting that they are going to bring un-invited guests with them... sometimes four or five extra people!!

Also, when we talk to them, they say vague things like, "Yes, we will probably stay for dinner" and "The grandkids may join us, depending on which car we drive up there."

This is driving me crazy!! They seem to think this is a pot-luck picnic, but it's a semi-formal event. We have a seating plan, etc.

Our caterer, photographer, parking attendant, tent rental.... everything hangs in the balance because these folks won't get the message and give us a clear idea of their plans.

How can I get the message across to my new family, without looking like an uptight bride?