+1!
For example, the Duplo Train parts should be in categories "Duplo" and "Train" IMHO.
However, this will change how the parts lists nowadays usually behave:
each part appears there uniquely currently, just a single time.
Putting a single part into multiple categories will break that principle.
Parts will show in various categories. We should carefully consider if this is
SIMPLER for the users or more CONFUSING.
For example, the Duplo Train parts should be in categories "Duplo" and "Train" IMHO.
However, this will change how the parts lists nowadays usually behave:
each part appears there uniquely currently, just a single time.
Putting a single part into multiple categories will break that principle.
Parts will show in various categories. We should carefully consider if this is
SIMPLER for the users or more CONFUSING.