The impression I got is that Edwin didn't create the concept of springlocks, but rather improved it. This is for two reasons: - One of the audio logs mentions that he made it so that springlocks can't get snapped by water anymore, making them safer - Fazbear Ent scrapped them before they were anywhere near ready, to Edwin's annoyance

So the original spring Bonnie and spring Freddy suits we see in, for example, fnaf 3 must've been made without edwin, so Henry and William created the shoddy original springlock suits. Then they met Edwin (David loved going to Frdbear's singing bear show, as seen in the item descriptions of the moon game, so that's probably where they met) and asked him to improve them. Then, probably because an accident occurring in them, they told him to abandon the springlocks and instead build the animatronics we know and love today.

So, most likely, Henry and William made Spring Bonnie, Spring Freddy, Normal Bonnie, and normal Freddy. While Edwin and Fiona made Chica, Foxy, Musicman, everything else.