In a few places in there is reference made to a new way to create associated symbols that allow full customization (my interest is footprint filters) compared to simple aliases but still maintain the sibling relationship
This launchpad bug has the most direct reference
Yes, there is support for properties in the new library file format
which can be used to create “fully defined” symbols that inherit from a
base symbol. It’s slightly different than the current alias scheme that
we currently use but much more versatile. Although this will most
likely change somewhat before the spec is finalize.
Is there a way to create these more general inherited symbols in Kicad 5.0.1? Is it supported by the new library format already?