either option gets you to the same result. the only difference is what size numbers you work with.
If you use total FMV, it would look something like this.
1,000 shares whose FMV at death were 10,000 dollars.
With a 2:1 stock split, you would now have 2,000 shares worth 10, thousand dollars.
So 10,000 divided by 2,000 = 5 dollars per share
The second method starts with the per share FMV as of time of death,
In our example 10 dollars per share.
With a 2:1 stock split it would be 10 dollars per share divided by two = 5 dollars per share.