The example in Partitioning with overlaps illustrates how to partition tables based on a criterion in some other table.
Some tables in your remote database may have disjoint subsets or overlapping subsets, but do not contain a column that determines the subset. These are child tables that usually have a foreign key (or a series of foreign keys) referencing another table. The referenced table has a column that determines the correct subset.
In this case, the download_cursor script and the download_delete_cursor script need to join the referenced tables and have a WHERE clause that restricts the rows to the correct subset.
For an example, see Synchronizing contacts in the Contact sample.