Different mail disclaimer for different OUs

Hello,

at the moment I am in the process to create the automatic mail disclaimers for our Company.
The problem is for the last part of the disclaimer we have 5 different versions.

In AD all the users that need the same version are also in the same OU.
So my question is what would be the best practice for the mail flow rules.

I saw that there is an option to give all users that are in the same group the same disclaimer.
But is there also an option to do this on an OU level, bc if I do it this way I
have to change the group membership every time a user is moved between the Ou’s

EDIT: We have exchange as part of Office365, I hope this is still the right part of the board to post the question