Without renouncing to PRs
Also, the 2 other kids who have PRs are 11 and 8 years old. If we stay in Canada for 6 months and then application to renew visitior's visa of the youngest child will be denied, could it be helpful to write that the Twovolder kids already got used to Canadian school so for children's best is to stay in Canada.
If you apply for H&C for your youngest child you will bring attention to the fact that you don't meet your residency requirements.