Baptising Polygamists - a missionary's dilemma

Keith Smith is a World Horizon missionary in Burkina Faso (tr. "Land of the Upright Man"). I discovered his blog - under the acacias- today and liked it a lot. This post is a thought provoking account of a cross cultural issue I'd never considered before. What do you do when a new convert asks to be baptised when he has more than one wife?
In addition some of the photos Keith has on flickr are absolutely stunning. I urge you to check out his great blog here.