Sorry to hear that!
IRCC is extremely strict about MNI. Even $1 short, would not be accepted.
Here is MNI for 4 persons:
2015: $57,642
2016: $58,768
2017: $59,426
2018: $60,271
If you are a 2018 applicant, IRCC has looked at MNI for 2015-17. If you believe your son's income has met MNI for...