Clean up and tear down of FIT fields onSettingsChanged?

Hi,

I have a range of data fields that have a dynamically derived collection of .FIT fields - one might choose to store a detailed set of stats for one metric, or a generalised set of stats for three metrics, for example.

All is good and it works well, but...

I've recently had a customer asking about visualising changes onSettingsChanged... which is all well and good apart from the fact that those settings affect the .FIT fields I need to build! And, if I build a set of .FIT fields and somebody decides to change the requirements, then I run into all kinds of issues with too many fit fields etc.

So...

Assuming that I do, as I want to, move all Data Field settings to respond to onSettingsChanged, what is the best place in the Data Field life cycle for me to build up the .FIT fields? Can I, for example, respond to the actual session start / stop to build the .FIT fields? If I do that, is there a way to tear down the old ones and clean up when the activity completes?

G