A shower thought...
All of the dependent returns that my practice handles are adult children who have reached the age of majority. They're usually attending college. I have these clients sign an engagement letter, and it usually contains a paragraph that authorizes me to discuss the return with the parent(s).
At prior firms, I was exposed to tax returns of minor children, who usually had a filing obligation due to investment income. Sometimes a high school kid that worked a W-2 and had income tax withheld.
I'm obviously not an attorney, but I think I read somewhere, at some point, that contracts are not binding on minors. Something about capacity and such and such.
For these clients, does one have the parent(s) sign the engagement letter for the minor child's engagement? Such as "John & Jane Smith, parent (or guardian) of Jimmy Smith"?