This is my collection of tools I use to offline update the install.wim files, and latter make multi-architecture (x86 and x64) install.esd files for each OS (7, 8.1 and 10), to let all them fit on a 16 GB FAT32 USB (2.0 or 3.0) stick and even have some extra GBs free.
Of course you must have required original Isos to make use of this.
I use some programs and batch files to update the .wim files as:
I strongly suggest to download all required files/folders and read authors instructions before start doing anything.
1 - WHDownloader from Alphawaves to download Updates directly from MS servers:
You need to extract WHDownloader on a folder on your PC (preferable on the root of a partition and do not use spaces on folder name).
See first OPTIONAL note No.8 at the end for additional info before downloading update lists.
Latter just run the program and download all Updates you previously selected (read carefully the info for each one, some are problematic like those to forced update to Win10).
2 - Also to install updates offline on .wim or on actual running OS, from abbodi1406 batch scripts you need: Windows 10 Updates Installer, WHD-Windows8.1-Updates-Installer, WHD-Windows7-Updates-Installer 4.5, but for Win7 I prefer Symplix Pack from Symplix. All this uses DISM to mount .wim and update indexes, and rebuild .wim
You need to extract the required abbodi1406 Updater(s) into WHDownloader folder located on your PC.
Just copy/move the install.wim to same folder before running the Updater batches, You may also modify them to select your prefered location for the install.wim if you want too.
3 - Optionaly if you want to remove/add something from/to .wim files as removing Apps, One Drive Desktop, Skype,
etc or adding Windows Data Deduplication, Direct X9c, enable Photoviewer, etc.. I use MSMG ToolKit from MSMG this uses DISM and wimlib-imagex
You need to extract MSMG ToolKit on a folder on your PC (preferable on the root of a partition and do not use spaces on folder name).
4 - Then to make a multi architecture install.esd you need to rename in x64 install.wim file all indexes adding x64 at the end of name/description, and latter export all or selected indexe(s) to an install.esd file to do this on a graphical environment (GUI) I use wimlib-clc from ReTokener a GUI for wimlib-imagex from Synchronicity
You need to extract wimlib-clc on a folder on your PC (preferable on the root of a partition and do not use spaces on folder name), open the folder an create a subfolder x86 or x64 (or both as required) and add libwim-15.dll and wimlib-imagex.exe (x86 or x64 versions) to the respective folder, I recommend download version 1.13 Beta 5 (the latest)
5 - BootIce v1.34 from Pauly
6 - RMPrepUSB from steve6375 to prepare the USB stick:
7 - Then before start, just read carefully all readme files contained on each download and follow instuctions from the authors, all instructions are very clear and easy to follow.
8 - OPTIONAL: If you as me prefer to do not install updates after December 2017 (on January started all the messed updates for MeltDown and Spectre), Do not update the Updates lists on WHDownloader, fortunately I keept a copy of December 2017 Updates list:
Just extract the 7z content on WHDownloader folder.
9 -Use WinNTSetup from JFX to install OSs:
You need to expand it on a folder on your PC and run it at least once to let it download some files/folders from MS servers, latter just copy it to your USB where you have your WinPEs and all .esd files on a folder for each one.
NOTE: For using majority of this tools it is better to disable AV and right click and run all of them as Administrator, what I do is create shortcuts on desktop and modify them to run as Administrator to do not forget it, also have all of them togeter and easy available.
Also as some Update tools and create a install.esd require high CPU and RAM usage I strongly recommend do not run any other program (including internet browser) when they are running.
IMPORTANT: When using MSMG ToolKit, at the time you will apply all changes and dismount the .wim image it is better DO NOT have any other window or program running, DISM is very prone to create troubles if you do not follow this instruction, the batch has code to prevent this issue every time you quit and run it, but it is better to be on the safe side.
I hope this info about this great tools for update OSs offline and latter install them may be useful for you.
The other forum (MDL) requires to make an accout to view some posts/links, I put all links to source to give proper credit to all authors of this GREAT tools, but there are links available for dowloads on the post for your convenience.