Like in the base story with companions sending you messages, have them start sending us mail which we can reply to. Obviously the answers would have to be prewritten like the dialogue wheel, but it would be an easy way to continue interacting with companions without having to pay VA's. Plus if more content gets released you really wouldn't even have to reference it much, if at all.
Example of mail
-Asking Akaavi why her guns itch so much and why she doesn't get some lotion for them
-Vacation plans with Vette
-The Bastion and Bastion related products with Pierce
-Freeing the ____ out of the Empire/Zakuul with 4X
-Needling Quinn about that one time he betrayed you and you didn't murder him
-Everyone losing it when Blizz gets into stuff and starts tinkering