I just ran across an interesting patent where the inventor is Ernest W. Campbell but instead of the assignor being Campbell-Metcalf Silver Co it is assigned to Holmes & Edward Silver Company. Bridgeport, CT & Providence, RI are only about 120 miles from one another so it does not seem entirely impossible that Ernest did work for Holmes & Edwards Silver Co.
I was looking for a wheat/sweetgrass with flower pattern for a souvenir spoon when I came across this patent along with four others like it.https://patents.google.com/patent/USD25018S/en?q=spoon&inventor=ernest+campbell&oq=spoon+inventor:+(ernest+campbell)
A Copy of Campbell-Metcalf Silver Co. also shows Holmes & Edwards founder George C. Edwards as a Formally associated to the company on it's officiall RI Certificate of Incorporation.
I also found an article stating that Providence, RI petitions insolvency and one of the assets were described as Holmes & Edwards Silver Co of Bridgeport, CT.