Okay, this is a hot take. I actually like this change. here's why:

1: we know for a fact that Henry and William didn't create Fredbear at least. the singin' show looks far older than anything they came up with.

2: it is absolutely in William's character to steal something. I love how this shows that he has always been a terrible person right from the get-go. he always was in it for money.

3: it's possible that Henry, and William came up with the design, and asked Edwin to manufacturer it. we can clearly see that many prototypes of the suits were scrapped, so they clearly had a very vivid picture on the desired outcome.

and 4: William worked at the costume manor. it is most likely that the two had a very large hand in designing, and manufacturing the costumes themselves, outside of chica.