There should be a “Suspicious Device” or something like that beside one of the tables on the main floor. You can meet Kasumi in the Silver Coast Casino.
Everyone else, including present ME3 squadmates not yet mentioned, are optional invites. Preview of the festivities ahead The bare minimum of people whose survival from the first two games are assured are auto- invited: Joker, EDI, Liara, James Vega, Steve Cortez, and Samantha Traynor. Who can you invite to the party Citadel DLC? just leave the apartment and come back, and each time you’ll get more messages from the squad mates, after which you can invite them up, or go meet them at the Strip. It’s always randomized who you can invite first. You’ll need to receive Tali’s “Housewarming” email before you can invite her up.