We need the ability to re-synchronize passwords from the Identity Vault for a selected user or users.

In other words, we need to be able to trigger an event that will send out the current password stored in the nspmdistributionpassword to all connected drivers the user is associated with.

Right now, there is no way to do that, that I know of.
A migration does not resynchronize the password. (unless you add a custom policy to do so)

I have had multiple customers ask for the ability to do this.

Yes, the driver(s) can e customized to do this, however it would be nice to have this feature out of the box and not have to create a customization to accomplish this.