[Right Wing Assault]

I'm pretty sure that the lower "77" handwriting belongs to Roy Moore's assistant, Deborah Adams.

What? How is his assistant going to get hold of the yearbook? Did the girl give it to Roy to take back to his office and his assisatnt finished his message? Then he takes it back and gives it to the girl?

[TigerClaws]

The theory is the accuser copied it from her divorce paperwork not knowing what the “D.A.” meant. She thought it meant “District Attorney.” He was actually a Deputy or Assistant (DDA or ADA) at that time in his career.

[Yosemitest]

The first source I used got the name wrong.
Here’s one more source:

Embattled GOP Senate candidate Roy Moore's attorney implies his signature in a girl's high school yearbook was a forgery

“ … "Judge Moore looked at that D.A. after that signature," Jauregui said.
“No, he wasn't, he was the assistant district attorney."
He added that Moore's assistant when he was presiding over Nelson's divorce proceedings was named Delver Adams,
who typically stamped his initials on court filings. … ”

I believe that it's a forgery from Mrs. Nelson's divorce papers with had that stamp.
I think it's either a traced copy from those papers,
or someone got Delver Adams' stamp and masked one side of it, in order to stamp the rest of that signature.

But ... I'm guessing.