Diachronics of plural inflection in the Gallo-Italic languages

The general lines of diachronics of Lombard and Piedmontese plural declension are drawn here:

Feminine
In Lombard and Piedmontese, feminine plural is generally derived from Latin first declension accusative -as (compare ); nouns from other classes first collapsed there; some concrete realisations are:
 * -as > -a
 * -as > -es > -e
 * -as > -es > -ei > -i
 * -as > -es > -ei > -i > -e
 * -as > -es > -ei > -i > -∅

Masculine
On the contrary, masculine plural is generally derived from Latin second declension nominative -i; this suffix eventually drops or gives rise to palatalisation or metaphonesis; some concrete realisations are:
 * -li > -lj > -gl > -j
 * -ni > -nj > -gn
 * -ti > -tj > -cc
 * Metaphonesis (in regression) : orti > öört;
 * Neutralisation: -i > -∅