In this situation divide the table on sections has'n any sence.

Main reason for sectioning --> query and indexing each partition seperatly
In this db model selectivity of indexes, that has to use your flag will be nothing.
I will be think about two tables with constant part of data and variable part.
Because:
-- we can use for first part something like read-only tablespace, minimal rollback contention and so on.
-- phisical characteristics of a table for variable part has to be another
-- dayly backup for read-only ts not needed

In queries we can use union (better union all for exclude sorting from execution plan)
for retrive datas from both tables.