I got my trust back in 2011 when I bought my first NFA item. It was the most recommended at the time, written up by David Goldman at guntrustlawyer.com. At that time, trusts were much easier, especially in my personal situation at that time, so that's the route I went.

I currently have (1) MG, (2) SBR's, and (6) suppressors on that trust. I'm thinking of buying a couple more cans, especially with the quick turn around times that I keep seeing, but with new(ish) headaches of using a trust, I'm debating if I should add any new items to that old trust, use the Single Shot Trust from Silencershop, or just file individually.

My dad is the only beneficiary currently on my trust. I'd like to change that since I am now married with 2 kids, but last time I checked it was something like $75 per person to add someone. Ive also never really understood the whole Schedule A thing, which I believe, is supposed to officially declare what all is actually in that Trust.

It's been years since I've added an NFA item to my collection, and most of that is because I just haven't wanted to deal with the paperwork. So I'm coming here asking for advice on what options I should consider before making another purchase.

My trust is 12 years old.  I last submitted a suppressor last year.  It's my 25th approved stamp.  Same trust.  I just keep adding to the last page with new items as they get approved.

Individual is definitely easier, but a trust gives you more flexibility. The problem is you now have to file photos and fingerprints for every "Responsible Person" in the trust. That is a pain.

I want to SBR a few pistols and get a couple suppressors and am leaning towards a single shot trust on a suppressor, then add the pistols to the trust via Schedule A and file Form 1s to make them SBRs. After getting the stamps back, I'll amend the trust to add the people I want as RPs.

That is perfectly legal and you do not need to notify the ATF when you amend your trust.  

You can have your trust restated. NGT

They also provide all the amendments to add/remove people with the purchase.

I made sure to get a Word document of my trust.
When ATF changed to all RP need prints, photo, background check I copied my trust, renamed it and deleted my wife as a RP.
So now I have two trust, one prior to 41F and one for everything after.
I also have a SS single trust on one can.

My LGS is almost as easy as SS, they do your prints and photo when you buy a form 4 item.
You just have to repeat each time which you don't with SS.