Add extra Lithium Batteries in Parallell

[treblid]

Buss bar length is irrelevant. Hence I said to calculate correctly it gets tricky. It's not the same as a cable calculation.
If you have a Lynx, 1000a bar, measure the bar and the result of mm2 divide by 10. That would give you min requirement of mm2 bar per 100A connected. So the bar is 8x30mm, 240mm2, that's 24mm2 per 100A.
The 12v planet sure its not a problem, as long as you keep the total ampacity connected to be ok with the 30mm2. It's the user duty to decide what it connects to it.
And don't even contemplate to run 500a through a 25mm2 bar, you will need 120mm2. You can also make it up by stacking multiple plates, as long as is bolted with spring washers, and the plates are completely flat, really flat.

Thanks for the explanation.

 

[CAB96]

Or do the Lithium batteries if installed need to be separated from the Vehicle charging system?

There are many, many threads about replacing lead acid with lithium, most common advice is that you need a new 'B2B' charger in place of the old 'split charge' relay.