I’m not going to dig that deep on that angle.
In 1974, he disappeared completely while going in Mexico. He was presumed killed, because...
While *Jim* Ac0sta’s father is supposedly Cuban, his mother is supposedly of Scottish background.
Other than lighter skin, I think Jim & Oscar look similar. Plus (alleged) birth year & disappearance year being very close.
Why would Jim keep the last name?
“Bloodlines”
“They don’t hide it”
If anyone was ever a Mockingbird, it’s Jimmy the Mouth.
Beyond the above, it’s pure speculation.