VSR charging, rocker switch, relays for canal boat

[Jjwills]

Hi, had the narrowboat for a little while now and having a few issues with charging and managing batteries. For some reason the voltage meter reading is dropping on both the starter and leisure battery when moored without engine on and don’t want to ruin the starter battery is this normal? Any help appreciated.

Wondering what the rocker switch is actually doing changing between 1 and 2?

Why have 2 x relay in what looks like parallel connected with a VSR?

The starter battery is wired to battery 2(aux battery) on the VSR which is opposite to any wiring diagrams I’ve looked at is this right?

Hope the pictures are of some help. Thanks