Darknet with differential learning rate

I want some tips on how to create a Darknet with differential group layers to be able to use differential learning rate.
I am training in images that are big, so I would like to train first with small ones, and increase size progressively. To do this, I would like to be able to train the bottom, and the head. I just want the same behavior that you get with a resnet34 model, but with a custom darknet or wideresnet, what should I need to add to this classes to be able to do so in V1?

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