What are the consequences of a 90-day report overstay for a dependent visa holder in Thailand upon departure?

The user seeks advice regarding the implications of an overdue 90-day report for their 2-year-old grandson, which is 3 days overdue. The grandson's parents, who hold dependent visas, have recently returned to Thailand within the 90-day reporting period, which renewed their reporting requirement. The user is inquiring whether a fine for the overstay will be enforced when their grandson departs the country and what the potential fine might be.