Thanks for the feedback Dennis. I am using the modified_on property currently. I think I have a solution that works for me.
I attached a method to a boolean field that simply saves the related item upon edit. And the modified_on field shows the time is was edited.
For some reason the save method attached to the boolean didn't move the parent back to the default view like the string data field did.
I previously tried a custom data field with date and time but it was relatively slow to populate.
I'll look at using SQL for future solutions if this comes up again.
