A child over 22 years old is NOT a dependent. He/she will NOT be part of the application and cannot be sponsored under family class.Will POF still be provided for such child over 22 years that is ineligible and not travelling with the parents?
Secondly, assuming you have another child that is eligible (ie below 22 years) but she's not going at all (either now or later) with you. Would you still need to provide POF for such?
There is no POF needed since he/she cannot be sponsored nor be included in PR application of parents.
btw there is no POF required (Family Class sponsorship) to sponsor your dependent child under 22 years old. This is WHEN you are already a PR or citizen.
I have no idea about POF on other stream of immigration.