Perhaps not all is lost, perhaps you can do the same as I did for your son and his games.
A few years ago I was informed that someone wanted to do the Battle of Grolle using
PlayMobil figures. Having been there with various members of my regiment I set about using bits of
Playmobil people to make them for the diorama.
I found some useful figures and parts on
eBay, and turned some more up in
Lidl one day. The changes were mainly done with masking tape or some miliput. I did the conversions based on the actual people from the photographs. One of my friends is quite tall, so I added some 1.5mm plastic card inserts to his body and his legs to make him taller than a standard figure. The brims of the hats were also done with sheet styrene. Facial hair is also important and while one figure came with stubble aready painted on, the rest had to have theirs painted on.
In the end the figures never made it to Groenlo, maybe one day.