Making Argument Diagrams in LaTex

I am trying to do my homework for Logic lesson in LaTex and I need to make Argument Diagrams. I have no idea how to make these in LaTex. All I think is doing it manually with TikzImage.

Below are some examples for Argument Diagrams. (From our textbook “Schaum’s outline Logic 2nd Edition”)

After searching on the internet I saw people doing Argument Diagrams with tikzcd. This is an example of something I did by copying other people's work.

        \begin{center}            \begin{tikzcd}[row sep=1.5em,column sep=0.3em]                {1} \arrow{d} \& {} \& {} \& {} \& {} \& {} \& {}  \\                {2} \& {+} \& {3} \& {+}\arrow{d} \& {4} \& {+} \& {5}  \\                {} \& {} \& {} \& {6} \& {} \& {} \& {}  \\            \end{tikzcd}        \end{center}

And here is the image of the output:

However, I want to add a horizontal line under the second row.

I couldn’t find any way to do it. Are you guys familiar with how to do such a thing?