Forgot to render a layer

Hello, I am still kind of new to the compositing system and rendering layers. So I accidentally put two parts of the same scene into different layers, and forgot about it, and when I rendered the animation, the second render layer didn’t appear. I decided to try to put the rendered video and the renderlayer’s Z into a combine Z, but it still looks strange, can someone tell me the best way to combine the layers and Zs of the videos? Thanks in advanced.

Are we supposed to reconstruct your render / layer / compositing setup just from that post !

Why make it deliberately difficult for anyone to be able to help you.
Supply some useful info. At the bare minimum a demo blend file and a series of annotated screenshots that clearly explain the problem

I meant more in a general term. Like if I had two touching objects in different renderlayers and you wanted to perfectly combine them.