There are a few Sith Inquisitors introduced in the TV show Obi-Wan Kenobi, two of whom are named the Third Sister and the Fifth Brother. During a verbal confrontation, the Grand Inquisitor says to the Third Sister:
You are the least of us.
This implies the Third Sister is ranked lower than the Grand Inquisitor and the Fifth Brother.
Is there any explanation regarding how the Inquisitors are named? Isn't it logical for the Third Sister to be more senior than the Fifth Brother?