If you are referring to the catering of food for them, most places practice charging you extra per head.
Example:
Your cost per table for Menu A is $1,000;
Therefore per head you are effectively paying $100.
Say, the number of Muslim guests at that table is 5 and your menu is a shared family style dinner (meaning they serve 1 big plate of food and every digs their chopsticks in). The restaurant will probably charge you extra $100 per head for the 4 muslim guests at the table.
If they serve individual portioning, then you may or may not be charged extra per head.
If happen to be able to fill that 1 table with 10 muslim guests, the restaurant may not charge you any extra. Or they may charge you extra by a slight bit (say extra $100 per table).
All depends on whether the restaurant allows you to bargain on these prices or not.
As for the food available, you will have to ask if the restaurant can serve you strictly halal food (they could possibly cater from outside and that may add to the costs). Otherwise the alternative would be for them to serve no-pork, no-lard and no-alcohol prepared meals for your muslim guests.
Its better that you speak with the coordinator to see what are your options and if bargaining is possible on these items.
