There’s a small how to guide in the Designer’s Guide that teaches someone to send random cards from a deck to specified locations via an Irregular Grid at the press of a button. Having succeeded in the little exercise, it possible within the confines of Vassal to:
a) Cause further clicks of the button to only replace empty spaces on the Irregular Grid?
ii) Create a check that notices when a card is removed from that location and replaces it with another automatically? (I assume this would use global properties and key commands, but I don’t have enough education with the platform to know how).