When creating 'Simon', Fritz replicated the real Simon's skull using a 3D printer, and used that for 'Simon's' head.

During his rampage in 'POPGOES Reprinted', 'Simon' threw Stone through the window in the pizzeria, and then began to tear him apart for parts once he was inside.

Assuming 'Simon' began to destroy Popgoes and the crew after attacking Strings in 'POPGOES Reprinted', 'Simon' probably attacked Popgoes first, then the squirrel sisters, then Blake, and finally Stone.

The amount of time the lasers in the vents are on for is actually longer than they are in the game. However, Fritz heavily decreased the time they're active when Strings is online, due to Fritz not fully trusting them, probably because of 'Simon'.

Because 'Heartless' Stone physically can not activate the 3D printers, or even use them, he is forced to gain assistance from another character, causing him to be the slowest to fully reprint himself.

Popgoes' hat has a green band around it because 'Toy' Freddy's hat also had a band around it. The 'Toy' animatronics played an important part in Fritz's life whether he liked it or not, so giving Popgoes' hat a green band acts as a way for Fritz to subconsciously remember them.

If it hadn't been destroyed in the "Fright Fire", Fritz would have given Popgoes 'Toy' Freddy's hat to wear, instead of 'Classic' Freddy's.

Fritz became an inventor because of 'Rowboatics Corp.'. Fritz was very interested in the animatronics the company produced, and the interest eventually led to him becoming an inventor. His interest in the animatronics they produced may have also caused him to visit 'Freddy's' and eventually work there as a night guard.

Fritz was afraid of the 'Withereds', and the 'Toys' when he was working at the 'New Freddy Fazbear's Pizza'. But, after the Bite of 87', his fears of the 'Toys' grew and his fears of the 'Withereds' shrunk. Eventually, Fritz fears were only of the 'Toys', and the 'Withereds' became an afterthought to him.

After 'Fazbear Entertainment' died out, and the internet became more complex and interactive, people online probably gave the animatronics related to the murders the prefixes we use in the real world to distinguish them between counterparts.

(This last headcanon isn't really about the 'POPGOES' lore, but rather the 'FNaF' lore. However, I believe it could be possible in the 'POPGOES' lore, so I included it.)

The Puppet came up with the idea to stuff the children's corpses into the animatronics at 'Freddy's' from the springlock suits. When someone isn't in a springlock, it's lifeless and has hard and rigid movement because it's in animatronic mode. When someone is in the suit though, it comes to life, becoming fluid and precise. This is what made The Puppet put the children into the animatronics, because they believed that if the lifeless characters had a person in them, they would be given life.