[RSwank]

Using the information the Col has provided along with what we already know, I think a good case can be made that William Henry Lucas was probably with David Harries (see link given by Leendert in post #4) “all” of the time. In particular, Harries (probably with Lucas) says he was first moved to Ambon on August 1, 1944.
“When the Americans invaded one of the neighbouring islands” could probably be referring to Morotai, which was invaded in September, 1944. At that point Harries (with Lucas) was moved from Ambon to Muna for six months where the death rate was 50%. The Col’s info has Lucas dying on Muna on November 8, 1944 and he is buried at Raha Village on Muna. The body is later moved to the Makassar War Cemetery, Celebes Island and then in 1961 (at the request of the Indonesian Government) to Ambon.