You're merging, not splitting. I assume you are going to use Y-adapters. This is not really such a good idea, especially if you DO happen to accidentally use more than one source at once. You could possibly damage one of the sources. It might work for you but I would use some sort of AV switcher. It might be a little bit if a pain in the ass but it will be safer and might even provide better results.
"All men are frauds. The only difference between them is that some admit it. I myself deny it."