Your relatives will hopefully be willing to trade the meat for the convenience, and it provides a good platform to introduce others to vegan foods. The caveat I mentioned at the beginning of the primer about not getting too nuts about your lifestyle applies no more than here. Simply put, animal products are almost everywhere. Unless you go live in the woods and make your own food you probably can't avoid using some of them from time to time. Again, your comfort level with this is up to you.
Many food products contain ingredients like eggs, milk, honey, butter, or other animal products.
An example of this is that most commercial margarines contain various dairy products. Other less obvious ingredients to avoid include gelatin, whey, and casein. This list is far from complete. For a more comprehensive list a good place to start is the World Wide Web. The Vegetarian Resource Guide has a good list of animal-derived ingredients and chemicals found in food.