FireCop, I don't believe the Single Shot Trust is set up to add another firearm. I'm pretty sure that's a single firearm trust, but additional people can be added.
So you need to get another trust set up, or just file as an individual.
Fill out the form 1. Get fingerprint cards. Get photos.
Date, sign, mail with $200 check.
It takes about an extra month to get the stamp, vs efile. Not a big deal, in my opinion.
Once you have the stamp, or while waiting for it, get the lower engraved.
Then configure as desired and have fun.
I would never build an SBR on an Anderson lower. I like many people have had dimensional issues with them. If I’m spending $200 to SBR a lower, it is going to be and Aero or other high quality lower.
You know that it's possible to check dimensions, condition, and usability before filing a Form 1, right?
It doesn't have to be an impulsive shot in the dark.
If the lower is good, the lower is good. It doesn't matter what name is engraved on it.
I used to hear the same things said constantly about Aero vs PSA lower receivers. You know who made PSA lowers at the time? Aero Precision.