Unwanted certificates

It happened to me a couple of weeks ago. It has likely happened to you, or will happen. You order a certificate and when it arrives find it isn't the person you hoped. I was chasing Jennie Margaret Child who was born in Carmarthen in 1903, appears in the 1911 census in the home of my grandaunt in Chorley, Lancashire, then disappears.
I thought I'd found her marriage in 1935 but when the much anticipated certificate arrived it turned out to be another Jennie Child.

One thing you can do with unwanted English and Welsh certificates is make them available through http://www.certificate-exchange.co.uk/. The site has been around since 2008 although not especially active - Alexa rank17,932,786. You can search certificates registered for free. To offer or receive certificates you need a free registration.
The other thing to do is add the information to a postum at FreeBMD which is what I've done. You can do that even if the certificate isn't unwanted.

Thanks to Christine Jackson for the tip about the Certificate Exchange.