Migrating from local to domain users - creating home folders

Hello.

I will be migrating our ReadyNas from local users to active directory users. I've created a simple bash script to move files and folders from old to new user home folders. There is however one issue. Home folder is created when user is loging in for the first time. I have to do a workaround. There is no way that I will be asking for everyone's passwords, forcing a change or wait for them to log in. I will be migrating NAS after the work hours so before I will execute the script I need those folders to be created with correct priviliges.

I've found that this can be performed by using "mkhomedir_helper USER" but it's not recommended.

I've also found something called "rn_nml -a user" - is there any documentation for this? Is this te proper way to perform what I want? Please give me any clues or maybe even solutions to the problem.
Thank you!
Cheers!