One thing that is important to consider here though that if she feels pressured or isn't sure about her mother being in there with her and feels anxious at the birth, it's only going to slow or stall her labour. I think you need to choose what you feel sure of, the article has some great tips on how to talk to them and perhaps even say, at the moment this is how I feel and I will let you know if that changes - after all, the most important thing here is what makes mum feel most comfortable in labour for it to progress well and have the best possible outcome.