If that's your only reason, then you shouldn't add a blog. The reason to add a blog is because you have something to say to a community of people who are interested.
Without that, don't waste your time.
First may I say how much I enjoy your newsletter, articles and forum. High Rankings is, in my opinion, one of the few paces to get good SEO advice.
I have expressed myself badly. What I should have explained was that the products which we sell are allied to the fashion industry and that it is my daughter will be blogging about fashion. And she is extremely knowledgeable and passionate about it. Because if she wasn't I realise the blog would be a waste of time. Me, I must admit it, I'm in it for the links and the effect it will have on our SERPS. Fashion holds little interest for me.
I hope you will reconsider my original question and look forward to hearing from you.
Thanks for your help.