Individual Losses Per Node?

I am attempting to train a 3 layer neural network that predicts maximum and minimum survival duration. The final layer has two outputs (corresponding to a prediction of maximum/minimum survival) and I have written a custom loss function. However I have realised that I need to apply the loss differently depending on which node I am evaluating.

What would be the best way of approaching this? Would I be better off training two separate models to predict maximum and minimum survival?

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Thank you