introduce part concept

please make a part the top-dog instead of symbols

hierarchy:
1: Part

under part comes:
2;A symbols 1 or more per part (not units) free from each others not carrying any part related data like value or part-name
2:B footprint (1 per part)

symbols are referred to by their symbol-name
symbols reside in libraries as they do today

parts also resides in libraries, part library

parts carry fields like tolerance, manufacturer, mounting type (SMD TH or pressfitt)
part once in schematic can also carry mounting option , example (NO_MOUNT) or (A,B,E) mount only in versions A,B and E

when you create a part you choose a footprint
then you add symbols to the footprint.
add this stage you countdown in a window remaining unallocated pins as you add along the symbols
this way you can see if you have surplus pins
also warn for pins used 2 or more times.
non allocated oins could manually be marked as NC

once all the pins are spoken for and nit double allocated you can mark the part as "finished"

with this you also et rid of your current troublesome footprint allication scheme /trash -bin/

we will all be happy

:-)