We have a site where in the footer we have been asked to change our links from the sister companies name to a keyword of a product that they sell, they theorize that this will rocket the term up the charts for them. So for example they would like to change Widget Inc to Spark Plugs and then the link would go to Widget Inc home page. What we don't want is the anchor text to be indexed for us, but we want to pass link juice to the sister sites. Is nofollow or noindex a better solution or is there no way of really doing it?