TPC does not use the Least Squares coordinates until you choose to update the survey. Instead, the adjusted coordinates are held in memory, allowing you to analyse the adjustment first.
When you update the survey, the adjusted coordinates overwrite the existing coordinates in the survey. TPC provides the option to protect the survey points once they receive the adjusted coordinates, insuring that the new adjusted coordinates will not overwritten by some other survey computation.
TPC also keeps track of which points have been updated via Least Squares.