I have been doing composites from day one but it wasn't for safety at the beginning. My kids NEVER sat still together in a picture. I used to have to take a picture of my son Maverick and then take a picture of Georgia at the same angle and put them together. 90% of the images I have of them for the first year after Georgia could crawl is a composite. Unfortunately I've lost all of the digital images due to a software crash (that will be a blog post for another day) so I don't have of those to show you. I do however have others to share.
I also do composites for the safety aspect for newborn photography. I have seen so many photographers just starting out thinking you can really put a baby on a prop and then just walk away. I specialize putting babies in crazy positions and props but I always do it safely. Sometimes you have to be creative in the way you take the picture and then you spend a lot of time in Photoshop, and when I say a lot I mean it! Some of the images I have spent over an hour to make sure they are perfect.
Here is an example of a composite to get an image with all of the kids. These boys are cousins and the moms really wanted on picture of them all looking but they were one and that was next to impossible without the help of Photoshop.
The next series are all of my newborn images that I use extravagant props, and sometimes siblings as props. As you can see in the before pictures mom and my assistant are always close by!
The moral of the story is never compromise the safety of the baby to get the shot! If you Photoshop skills are up for doing a composite to do it safely then practice until you are able to!