For whose who don't want to use Dual Sheath Redux and looking for an alternative, Auto Unequip Shield to Back by 7StarC is a very easy-to-use and lightweight solution.

Supported follower list (I'm open to user's request) :

All followers which are members of WIFollowerCommentFaction (like Inigo)
Vilja in Skyrim by Emma
Inigo by SmartBlueCat
Arissa - The Wandering Rogue (V2 & V1.3) by Chesko and Nikkita
Companion Selene Kate - Kiss Me by Kasprutz and Hello Santa
Sofia - The Funny Fully Voiced Follower by John Jarvis and Christine Slagman

Summary of features bring by original mod:

- Favorited shield is worn on back
- Shield is auto-equipped when weapon is drawn
- Shield is auto-unequipped and placed on back when weapon is sheathed
- Choice between vanilla style (non-favorite) and back shield style (favorite)
- Optional register of weapon/shield combination
- When registered weapon is drawn shield will always be auto-equipped as well
- Torch equipping/unequipping supported
- Works with any shield
- Any shield can be auto-unequipped/equipped
- Any standard or DLC shield can be worn on back
- Auto-unequipping/equipping without delay
- Works with any skeleton (this mod does not touch your skeleton)
- Works with any armor (this mod makes use of shield slot only)
- Skeleton ShieldBack and custom Dual Sheath Redux shield support
- Follower support for 1 to 10 followers (tested with AFT and EFF)
- Dynamic DLC support (no DLC required)
- Only event triggered scripting (equip, unequip and animation events)
- No polling scripts!

Original mod could support up to 10 followers but only build on vanilla framework.
The purpose of this mod is bring these functionalities to the others.

Installation

• Install Auto Unequip Shield to Back by 7StarC (and read its description page)
• Download this mod
• Must be placed after your follower mod and Original mod
• If you want to use multiple follower compatibility patch, open plugin in TESVEdit and merge edits manually
• That's all !!
  

How to use :

• Give a shield to your hired follower
• Use dialog topic: "You don't need your shield now" (only displayed when your follower have a shield equipped)
• To stop support, use dialog topic : Grab your shield
• That's all !!
  

If everything is ok, your follower will have his shield on back when he is out of combat.
When you ready your weapon for a fight, your follower (vanilla or custom) will not grab his shield BUT when combat start, it will be equipped and used as usual.
Original mod works that way so this one too.

FAQ :
Q- My follower doesn't always have is shield on back ?
A- That is because the follower AI is not influenced by the mod. And the shield on back is only visible if equipped by the follower AI. So, the follower still does things his way. Meaning if you have an Archer type follower he will use his bow rather than equip the shield given to him. And the Greatsword follower will prefer a 2H weapon before using a 1H weapon together with the shield given to him (Thanks to 7Starc for explanation).

Q - How i do If I want to use XXX and INIGO together ?
A- You need to use the plugin dedicated to your follower, INIGO is great and works with all of them

Q - How i do If I want to use XXX and YYY together ?
A - You need to open plugin in TESVEdit and merge edits manually except if your followers are members of WIFollowerCommentFaction (like Great INIGO)

Q - Can i add WIFollowerCommentFaction to my follower ?
A- No, if mod author didn't use this faction, he certainly have a good reason.

Q - I don't understand how to do this, can you do it ?
A - Yes, I can but i'm not always at home, maybe if i'm not lazy i will post a tutorial

Q - Post your tutorial lazy boy !?
A - Maybe, maybe not, ask nicely ;)

Q - Your mod kill my game !! Ass*****
A - No, it can't and if you haven't a backup, it is your fault (valid for all mod).

Credit :
7StarC for Auto Unequip Shield to Back
Emma and Smartbluecat for their cooperative work on Vilja and Inigo.
Chesko and Nikkita for Arissa - The Wandering Rogue (V2 & V1.3)
Kasprutz and Hello Santa for Companion Selene Kate - Kiss Me
John Jarvis and Christine Slagman for Sofia - The Funny Fully Voiced Follower

My releases
Skyrim SSE:
Guide - How to repair your skyrim after update - Unbreak your prefered skse mods
Skyrim Save System Overhaul
Auto Unequip Shield to Back Custom follower compatibility patches
Keep It Clean - A Bathing Mod (based on clioshand work)
M'rissi's Tails of Troubles SE - Delayed Start
Compatibility patch for Brotherhood of Old and Skyrim sewer
Invisibility Glitch - Eyes Fix SE with Support patches
The Eloquent Reader - True Scholar SE Edition
Better lighting for Face Light SSE
It is mine - Claim your property (Change bed or crafting station ownership)
Camping and Frostfall - Unofficial SSE Update

Skyrim LE :
Stability Performance Optimization ENB Configuration - a Comprehensive Guide
The Notice Board by MannyGT UPDATED
Auto Unequip Shield to Back Custom followers compatibility patches
Glass fix for Wearable lanterns SMIM patch (optional HDTPE support)
It is mine - Claim your property (Change ownership)
Patches central for Invisibility Glitch - Eyes Fix and Invisibility Eye Glitch Multifix
Technicolor Alchemy Overhaul - Support for Wiseman303's Flora Fixes and CACO
Higher Difficulty - Adjusted Encounter Zone and Leveled NPCs
The Sober Soldier's Supply - Lore-friendly Wine and Mead Smelting CACOIFIED
Better lighting for Face Light and Facelight Plus
Simple bathing (in collaboration with clioshand)
[url=https://rd.nexusmods.com/skyrim/mods/88324]Moonlight Tales Essential - Unable to equip chest armor bug fixer