Consult a lawyer immediately.

Surely you will be in big trouble if your application documents are not same with your actual immigrant situation.

One of my friends had the same problem before, he submit the application for his wife, first boy and himself, then got the landing paper. but before he did landing, he had the second boy and unfortunately he did not applied for the baby.

Thus the officers in the Canada Custom refused their landing and took out the landing paper. The family fought with the government for 3 years by apealing to the highest(? not sure) Court and changed several lawyers before they got the final triumph.

It's really difficult and the whole procedure is absolutely time- and money- consuming.