Why do you have to do it? You are a Permanent Resident. If anything, you should convince that you will stay in Canada for 2/5 years
. The TRV is for your kid and it is usually approved (unless the kid is medically inadmissible) or if there are some other issues.
I suppose you can keep extending the TRV for your kid as long as the PR application is in progress and once a decision on the PR application of the child has been made, the child can become a PR.
Please direct this question to senior members like Leon/Scylla as they will have seen many such practical cases.
Good luck!