There seems to be some misunderstanding about resistor wattage ratings and heat transfer.
Resistors with a higher wattage rating can dissipate more electrical energy and heat (measured in Watts) before failure.
Given two independent resistors of equal resistance, one 1/4 Watt and one 1/2 Watt. If 1/4 Watt of power passes through each, each resistor will radiate 1/4 Watt of heat.
In other words, all other factors being equal, resistors with different Wattage ratings will transfer the same amount of heat into their surroundings.
I would suggest in addition to using blocking diodes to also select resistors with higher resistance values. This will reduce the current flow in the circuit and the heat. If possible relocating the resistors where they have more air flow around them would be a good idea.
