The aux sends can only be set globally, unfortunately not per input channel.
So you have to decide whether you want to set the aux send PostEQ or PostDelay. And this then applies to all signals in the aux path.
I usually use PostEQ for monitor paths so that the musicians can control their dynamics better.
A solution for you would be:
Create two aux paths. You make one aux postEQ and send the singer’s signal into it.
The second aux channel is postDelay, where you send the signals that should be in the monitor with their compression.
And finally you sum up these two aux paths in a matrix.
I know: that’s a bit complex again, but your task is a bit special. Of course, it would be nicer if you could set the tap points per channel. But then we can also make mistakes much faster 😉