The answer to your query about the location of the West Derby Cemetery. It is in fact what is now called the East Main Street cemetery in the city of Newport.
The City of Newport has a certified true copy of a vital record index card dated Dec 12, 1919 which shows East Main as the burial place for a Joshua Church.
In an aarlier post to one of your queries I gave you some research information, quite long. I probably should have wrote that all the cemeteries on the East side of the lake were, in there early days part of West Derby, Salem or Derby. The only one of the ten that I wrote about that was not in that area was the Holebrook cemetery often referred to as the Lake Road Cemetery, it is on the West side of the lake.
I also wrote that the list for those buried in East Main did not contain your Joshua for reasons stated. On Edit I think there was another individual who worked on that effort or is familiar enough with it to possible answer a question or two. That individaul is Ernestine Pepin, EMail firstname.lastname@example.org
or the contact may be made through the Memphremagog Historical Society.