Theraven's advice , as always , is very sound. Don't risk messing up your hood with families already packaged in lots. Another item that will help you fill up your restaurant can be found here...
http://simwardrobe.com/ go to Sims 2 , objects , business facilitators and grab the customer limit adjustor. It is really useful , keep in mind that your computer specs will be the final decider of how many sims can be on a lot at the same time. Just experiment until you find a good number. Good luck!