I have just listened to AUDIO: Buried Secrets and the behind-the-scenes extras. In these, Gary Russell states in a conversation with Paul Cornell that she was created as a Doctor Who companion, but she "left the Doctor Who universe" in her own stories. Therefore, if such statements about Vienna Salvatori are taken as her solo stories according to User:CzechOut in Thread:125464 not taking place in the DWU, so should all Bernice Summerfield stories that do not feature the Doctor.