My son just reported to me that his teacher from last year (a reliable source) told him that Monday morning Mass was an acceptable replacement for Sunday Mass. I have never heard this! His teacher said it was okay, as is Saturday afternoon.
This would be helpful for us because sometimes my son is with his father on a Sunday and then we have to drive a long way for a late day Sunday Mass, when we could walk to morning Mass on Monday. But I never heard it could substitute legitimately. Does anyone know?