You know my situation about my non-PR child staying in my home country. I decided not to sponsor my non-PR child until I make 730 days. But I have a question. When I apply for extension of my PR and will be asked why I have not sponsored by non-PR child so for what should I answer?
You have no obligation to sponsor your child so it is nobody's business. However, if that happens after you have already completed 730 days, you could safely tell immigration if they ask that you did not sponsor your child because you did not meet the residency requirements. If they did not report you for not meeting them at the time that you didn't meet them, they can not do it retroactively later. They can only look at the past 5 years at the time they examine your status. Once you have your 730 days, it is too late for them.