I completed the FAFSA form with my son the way the instructions say we should: my son is the primary user and has his own login. I took care of the parental section of the FAFSA form using the “Save Key” (shared password on top of our own private logins) that my son picked and shared with me for that purpose. We both signed the form electronically.
As @ClassicMom98 stated, the information retrieved using the IRS DRT tool is encrypted, but one has to manually input the W2 wages from each parent in the FAFSA form (I assume because the 1040 form aggregates wages from both parents), as well as parental assets. So the student can see the wages from each parent and the combined parental assets. The only thing the student cannot directly see is unearned income.
I found it a bit awkward to have to share all that information with him, but I guess it helped him understand why going after merit was important to us.
And once the form is submitted, only the student gets to see the SAR. I had to ask my son to send me a copy.