When you plan a party, it is important to have a general headcount. Especially when you are cooking on the grill, where everyone gets a piece of something. What do you do when people start bringing extra guests? Here are some tips (other than sending the strangers away-bad karma).
Add a simple side (s)
Have a few standby recipes that you can pull out at a moment's notice. One favorite trick of mine, is cutting up fresh fruit and mixing in yogurt/sour cream and a little honey. Then sprinkle in some cinnamon or nutmeg. The more people, the more pieces of fruit. Easy!
Cut the protein into smaller pieces
I know, you meant for everyone to have their own T-bone, but a serving is actually only 3 ounces, you can get at least two servings per steak. If you add the above side dish, no one notices a thing. Worse case scenario, slice all meat ahead of time and arrange on a platter.
Make more snacks
It is much easier to pour more crackers in the bowl, cut up more vegetables and top off the dip bowl. Fill them up on the little things, and their main focus wont be your grill. Running out of chips? Cut tortillas into wedges and spritz with oil. Bake at 350, until crisp. You get at least 8 wedges per tortilla. Dip all gone? Mix mayo/sour cream and all the herbs you like in a bowl. Perfect!
Put another veggie on the grill
Because they grill so quickly, adding another veggie to the mix is fast and easy. Slice on the bias, toss with olive oil and herbs. Voila'! No one needs to know it was an afterthought. One of my favorite tricks, is to peel a large onion, wrapping it in foil and adding a bit of olive oil. These grill up wonderfully sweet and seem a bit extravagant. Last minute guests? Slice onions first, and wrap in foil pouches instead. This speeds up the cooking to about 10 or 15 minutes (your meat needs to rest at least that long, so you have time).
Above all else, don't panic. Chances are, your surprise guests are feeling just as awkward as as you are. Just enjoy the party!