Boiler System with Regulator and Auto fill. Do I need both?

Hi All,

Newer to this hydronic boiler repair world and boy has it been a journey in a week and a half time! Had some workers come out and replace my circulator pump but instead of just isolating my circulating pump they drained my system dry. When the water was turned back on it wasn't autofilling. They replaced the PRV but still nothing. My expansion tank was pretty old looking so I just went ahead and replace that too, still nothing.

I replaced my pressure relief valve too because that was dripping slowly after they fiddled with it and it never fully re-seated itself, drip is gone now! So hopefully I fixed my leaky part.

I've been having to manually fill my system through my boilers drain line and have made sure to keep the cold pressure around 12psi. Alot of running around or having a friend at the boiler controlling the pressure while I bleed the system at each.

I've confirmed I have water on both sides of my backflow preventer so the only thing left is the autofill device. It's and old Taco T-joint type that I haven't found a direct replacement for it. The thing that I haven't been able to wrap my head around is why would you need a PRV and autofill. It seems like I should just need a PRV and I can just replace that autofill with a copper T-joint.

Thoughts?

I should note, I do want to confirm any system leaks are gone first before I potentially mask something with the autofill functioning again. But want to understand what/how I should upgrade.

Thanks!