Wisconsin is similar to what Newday describes. The law here also specifies that there can't be any modifications to the stock passenger pegs to accommodate the passengers reach. I read quite a few motorcycle publications and I don't recall seeing anything like you are asking about.
In the US most states have a law preventing you from carrying a child or person who cannot reach the foot pegs with their feet. This results in very few if any devices for carrying children on your motorcycle.
What are the laws in Lagos, Nigeria concerning carrying children on your motorcycle??
I have a brother and sister in law who have lived in Cambodia for quite a few years (they are currently stateside while she heals from a moto vs dumptruck crash. She and their 2 year old were on the moto). Over there, if you can get it on the bike, you can go. Not so smart though. Just because you can do something does not mean it is wise.