Before I purchase Backlight, I want to see if I can bulk add client logins (I supply both email and password) and then assign them to a group of albums all at once. I shoot events with over 1000 people and want to add a way for people to select their images through the feedback option or possibly use the cart option. In order for people to have the ability to favorite images they want while going through them at their leisure, I imagine they would each need a unique login, correct? Is this something that can easily be done? Thanks!
Have you looked yet at the differences between managed and unmanaged Client Response albums? You may just be able to go with unmanaged, which means you wouldn’t need passwords.
If you need them to log in separately, there’s no way I know of to bulk assign an album to individual clients. In Backlight, you’d go to the Users > Clients area and assign albums to each client, one at a time. And you would first have to create the client in Backlight (though it’s possible that could be done by importing data to the database. But that would be another topic)
That just might work so long as they complete their selections in a time but that is on them not me. 
Thank you!