Bummer that the auction houses aren’t offering anything helpful. A few more thoughts, which may or may not be helpful.
Circa 1900, the British company John Harper & Co Ltd of Willenhall illegally produced direct copies of mechanical banks from both the Shepard Hardware Company of Buffalo, NY and the J &E Stevens Company of Cromwell, CT.
As far as I know, Harper were never bold enough to include the original maker name on their copies, but perhaps there were other companies who had no such scruples, effectively producing contemporary counterfeits rather than copies. Harper did however include the original patent references for at least the first few years of production, after which they removed the information (perhaps in fear of legal action for fraudulent use).
Harper copies can be distinguished by either the absence of the patent references (on their later production), or from minor details such as drill-tapered holes, or the use of alternative materials. This Harper copy (an early one, with a fraudulent patent reference) for example has a cast-iron coin-arm rather than the pressed steel used for the original. Sincere apologies for the ‘N-word’ and the racial stereotyping, which I show only in the interests of historical accuracy.
If yours is a copy (and bear in mind that there were contemporary copyists/counterfeiters as well as more recent ones, such that the screw types would be similar) then the producer would have needed access to an original, or detailed drawings of it. If it’s a counterfeit rather than a copy, one would have to question why the baby was replaced by the child. There’s no record of Stevens having produced a ‘child’ version but, then again, the ‘baby’ version was unknown to collectors until 1955. The fact that only one surviving example appears to exist suggests it may have been a short-lived design. Perhaps a copyist found the child easier to cast, or judged it to have a wider appeal? It can’t have been in the interests of avoiding legal action for plagiarism, otherwise why leave the original manufacturer name on it?
If it’s a more modern copy, it’s generally the case that leaving the original manufacturer name in place is ‘safe’ if the company is defunct. Stevens was bought out by Buckley Brothers of New York in 1950, so it would likely be after that date.
As I said previously, copies of banks like this have been widely-produced for collectors for many years. Here’s a couple from my collection, both produced in Taiwan and about 35 years old, although neither have any original manufacturer names or patent details as part of their castings.