If you want to parallel diodes/transistors, you'll also need to make sure they have positive temperature coefficient - resistance goes up when temperature goes up.
If resistance goes down when temperature goes up, if one diode takes slightly more load and heats up, the resistance will decrease, and it will take even more current, which causes it to heat up more, and take even more current...
Eventually it will take all the current, and pop. Then it goes to the next one, etc.