Is there any way we can get cumulative sum of Time Spent and Time Tracking values?
Accepted answer
You can uncheck that box, but then both data is independent and you basically end up with totally unrelated data. I don't know how you would/could consistently report in this scenario and it does not at all make sense to me.
Comments
The thing is ,Time Spent tab is already implemented before Time Tracking. Users manually entered values in Time Spent. Now I implemented Time Tracking and did what all you mentioned above like Synchronize Time Spent with Time tracking and read only. Its working properly for new work items but work items which are created before implementing Time Tracking contains some existing data in Time Spent field. But when we are trying to add time using Time Tracking tab, it is erasing the whose value which is already present in the Time Spent Field and showing up only the values which are entered using Time Tracking. So now the data which exists in Time Spent for old work items, how can we add with time tracking so that there wont be any inconsistent data.
You can't have it all. You could add a custom attribute and move the old time spent data into that and you could calculate the real value from the sum of both. You will have to consolidate the data, otherwise this is not going to work for you.