The scenarios I gave in the videos are just so that you can through the whole cycle and understand how components work. The possibilities are endless.

The main connection point between invoice and SLA logic are: Event Classes and Event Type.
Each class and type combination will result into a journal. That is how SLA will work.

If you wish to split invoice line into two then you can use invoice distribution sets. This way you could have 2 distribution lines for one invoice line.