Sorting order of items in nested table

[lswmalloy]

In Appsheet, I have a table of departments, which links to a table of people in those departments. 

I'm trying to create a report template that lists out the people in each department, grouped by department and sorted by last name.

I want something like:

Department 1

Adams, Joe	Smith, John	Zarha, Tim
Day, Sara	Wright, Julie

Department 2

Andrews, Mary	Rega, Tim	Smith, John
Bendi, Sue

I have sorted by department and then made a nested table to make the three columns.

<<Start:ORDERBY(SELECT([Related People][WID], MOD([_ROWNUMBER], 3)=1), [Last Name], TRUE)>><<[Last Name]>>, <<[First Name]>> <<End>>

<<Start:ORDERBY(SELECT([Related People][WID], MOD([_ROWNUMBER], 3)=2), [Last Name], TRUE)>><<[Last Name]>>, <<[First Name]>> <<End>>

<<Start:ORDERBY(SELECT([Related People][WID], MOD([_ROWNUMBER], 3)=0), [Last Name], TRUE)>><<[Last Name]>>, <<[First Name]>> <<End>>

This sorts by the row number of the People table, not the last name. Since the people were not added in alphabetical order I end up with something like this. 

Department 1

Smith, John	Zarha, Tim	Adams, Joe
Wright, Julie		Day, Sara

Department 2

Smith, John	Andrews, Mary	Rega, Tim
	Bendi, Sue

All the people are in the right department, but not filling out the columns evenly (and therefore not sorted by last name appropriately).

Is there a way to create a virtual 'rank' column that I could use to create the table layout instead of the row number? Or any other ideas?

Ideally, the names would be sorted first vertically, then horizontally, but I would be alright with horizontally then vertically.

Any help would be appreciated!