Adjusting FIN Channel Parameters

One of my customers has used an MD4 on their hydraulic test system where they are driving a hydraulic fan and reading its speed with a frequency input channel.

In the future, they want to use different fans which will mean they need to change the working parameters of the channel (Max and Scaled Max values) and they need to change the values without changing the software.

I cannot find a way to do this at the moment, as FIN properties don't seem to accept integer parameters as inputs, nor can the channels be added to Adjust Items / Groups. 

Is there a reason this is not possible, even though many different IO channels can be added to adjust groups?