I strongly second Steven Lasky's statements on how people buried in a
particular landsmanshaft or other society's cemetery plot may not be
associated with that town or ogranization, and I want to add another
reason for it -- many societies sold individual or pairs of graves to
"outsiders" as their membership declined. They usually did (or do) so
because they realized that they had a lot of space that would go otherwise
unused and as way of raising money as their revenue >from membership dues
declined. Some groups probably started this practice regulary as early as
the 1960's, and occasionally did it even earlier, although the actual
deaths may have occurred much later.
Note that this is technically against the standard agreement between
the cemetery and the landsmanshaft or other organization, which among
other things allows groups to bury only their members and immediate family
in their plot.
So even if you determine that somebody was indeed buried at a time that
a landsmanshaft owned a particular plot and was still active, you can't be
sure that they were connected with that town or organization based only on
that type of information, especially if the death occurred during the
group's waning years. Like all other secondary information, other
A Chag Kasher V'sameach (happy and kosher-P holiday) to everybody.
New York, N.Y.