Does the change in age of dependants affect sponsorship undertakings for dependent children?

Yes, the change in age of dependants affects sponsorship undertakings.

As of October 24, 2017, the length of undertaking (the length of time you are financially responsible for the person you sponsor) for dependent children has changed:

• If your dependent child is less than 22 years of age when they become a permanent resident, you are financially responsible for them for 10 years after they become a permanent resident, or until they turn 25 years old, whichever comes first.
• If your dependent child is 22 years of age or older when they become a permanent resident, you are financially responsible for them for three years after they become a permanent resident.