From what you state, it appears to be unnecessary. If there are no
additions or subtractions on
Form
MO-A that apply to your son, there's no need to submit it with Form
MO-1040.
In "Information
to Complete Form MO-A, Part 1" in the Instructions
for Form MO-1040, the taxpayer is advised that if "If after reviewing
the instructions for Part 1, you have no modifications, enter on Form MO-1040,
Lines 3 and 5, the same amount(s) entered on Form MO-1040, Line 1."
