Probably too late now - only just logged in but...
I've had huge numbers of plums to deal with, and unfortunately have ended up throwing a lot away as they began to rot. However, I have made a batch of jam from them, I've stewed a load down and frozen them in bags, for later use probably in crumbles and have also frozen some simply stoned and halved in tuppers, and covered over with sugar syrup.
There's food for thought for any of you still with plums to deal with.