Solution
Go to:
[1. input/edit] - [1.1. Sows] - [1.1.2. Sow disposal]
These menu options allow you to sell multiple sows at once.
Sows can be sold in three ways:
Move or drag the sows from the left column to the right column.
Select the sows in the left column (by checking the box); moving them to the right is not necessary in this case.
Enter animal numbers in the empty row of the right column.
In the disposal details section, fill in the fields that apply to all selected sows (e.g., disposal date).
Enter the reason for disposal for the individual sows.
Click the green checkmark to save the disposal details.
Once a group sale of sows has been entered, you can only modify or delete the records on a per-sow basis via menu 1.1.1.