I bought a pack of 10 - 2 each of 5 different snap sizes. Supposedly the different snap sizes correspond to various clothing brands. To tell them apart I marked each pair with a symbol using a permanent marker.
After I marked the extenders I tried them with his wardrobe and discreetly tagged each onesie with the appropriate symbol.
Here you can see how an extender adds a few needed inches to a onesie.
Now take a gander at an extender in action. Admittedly, Luke looks a little silly wearing his extended onesie...
Just so ya know, no one paid me or perked me for mentioning this product. It's just something I found on my own and wanted to share with you guys.