I think it can actually be very beneficial for your daughter. This way, she will be growing up bilingually, which is awesome. We have a similar situation at home: I speak German to Lilly, hubby English and her nanny Afrikaans. She clearly understands all three languages. These little ones are very smart.
Initially, I was concerned about language confusion, too, and I read up quite a lot about it. It's best for the kids to associate each language with a person at home. She will figure out quickly that you and your DH speak Afrikaans with her and her nanny English. In a multilingual country like SA, this can only be beneficial.
Good luck with the interviewing!