From your other posts, I see that you have included your son as not accompanying. You now want to change his status to accompanying? You can do this but in fact, the criteria for him to be considered a dependent child and get PR under your application, would have been that you applied before he turned 22 which would have meant that his age was locked in or if you applied after he turned 22, that he was a full time student since before the age of 22 and financially dependent on you. He is now enrolling at 23 so that criteria is not filled. However, you can check if you get away with it and change his status now to accompanying. If he gets his PR, he should move to Canada because if he stays in the Philippines to complete his education, he will have two problems. 1) He will have been outside Canada for too long and may lose his PR because of that and 2) His education will not be worth the same in Canada as a Canadian degree would be.
If you are unable to bring him now, it will definitely not be easier to sponsor him later. It is very hard to bring adult children as they are not considered to be a part of your family unit. If you miss this chance now, the best you might be able to do would be to try to help him come to Canada on a work permit or a study permit so he can immigrate himself.
