The split-year election requires all affected shareholders to agree in writing to split the year. In the absence of that election, he gets per-share-per-day. To effect the election, you figure out separately what each K-1 will look like, then override all the K-1s to match that. The one I did took two Lacerte files, 4 times as long as the return would have taken using per-share-per-day, and a ton of tedious swapping pages. Also, the return had to be paper filed.