Sounds like my mother in law. Get ready, it just gets better. Just get used to them being around... Like, All. The. Time. Sorry OP.

If they're not actually staying WITH you that additional week then you should just deal. Getting to destination weddings is expensive, it makes sense they would want to stay extra time and see something other than your wedding.

Maybe they just want to continue their vacation since they will already be there. Just call the resort and have your room as far from theirs as possible. Plan your activities as if they weren't there and tell them you'll meet them for dinner one or two nights. Otherwise, just avoid them.

I think that you should put your foot down, hun. This about YOUR wedding and honeymoon, not a holiday for your in-laws. It's just a line that I wouldn't let my in-laws, or parents for that matter, cross.

Yet another entry on a long list o reasons why I personally consider destination weddings pointless.

That where I was born!

Op just tell them straight up that it is not okay with you/your fiancé. It's much easier to argue about now than when the wedding gets closer.

tell them to **** off

You're marrying yer man. Not his family. They don't get to decide if they are going to go to yer honeymoon. Stand up for yerself.