As title suggests, provided a PoD in the mid 18th century that’s guarantees survival of the Commonwealth (leaving that up to your imagination) and presuming a butterfly net creating a somewhat similar 19th century, how would the Polish-Lithuanian state handle nationalistic impulses/national awakenings? They ruled over a land arguably as diverse as Austria, who managed by keeping the minorities at eachother’s throats. Poland may have an advantage as a Slavic country ruling over other Slavs, so a state sponsored pan-west-Slavic thought could be on the table, no?
For the purposes of this, the borders can either be pre-partition or after first partition