Try something like the schematic shown in the image. Here I am taking 5uA reference current, converting it into a 1uA current and then generating the references for the 1uA current. You can change according to your need.
The different colours mark the different bias lines.
As long as the input bias current is constant, the bias voltages would correspond to it ie it would track across process and temperature.
Also the sizes should match with what you have in your circuit for the best matching.
For the size of the cascode bias generators namely mpb21/mpb22 and mn10/mn13, the size of the bottom device(mpb21/mn10) should be about 1/3 of the size of the top device(mpb22/mn13). You can derive this since the bottom devices are in triode.
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