Party SmartAdd is similar to SmartPost, but for Sonlet Parties. 

From Sell -> Listings you will see a new Party SmartAdd tab next to the SmartPost tab:


If you are an admin of the Party, you can create Custom Albums right from the SmartAdd page, or just stick to the "Auto" style-based albums. 

From the Party SmartAdd screen you can add your items to custom albums or regular style-based albums.