Hello Mel,
I am unable to make any real sense of the detail of your question. Most caravans do not have 'inverters' fitted. If yours does it may not be a standard device, and this makes it difficult to offer any practical advice that will be safe.
Even though you seem to be referring to 12Vdc systems, even 12V dc can be dangerous. there is a serious risk of fire if a battery is shorted out even for just a few seconds.
I think it would be best if you contact your supplying dealer, or arrange for a qualified electrician to re-make the correct connections.