Sounds like they’re trying to use that relay as an ignition switch replacement.
By one wire “joining” another, do you mean two wires into one or the coloured wire listed then turns into the next listed colour, remaining as one wire in the system (like a piece of wire added to lengthen the factory wiring)?
Time to bust out a multi meter and find out which of those unknown wires are earths. If no earth wires are in there it’s time to put power to each wire individually to see what that wire operates - you might have to go and flick switches in the car to find out. There could be multiple items on one wire. Draw a diagram to keep reference
Some of those wires sound like main power or main switches power wires for accessories. This is partly concerning as the load on that relay is most likely too great for it to properly handle, plus there’s a question around how these wires are fused between the battery and the relay.
You might also find some of these wires (or all!) are the main switches power wires to the fuse box under the dashboard.
After you’ve done all of the above, it’s time to work out what they cut out, why, and what they were intending to achieve. Then reverse their work back to the factory setup or to something that’s safer and more serviceable for you to work with.
Sorry for the essay! I feel like you’re close to having this one sorted with a bit of work involved!
Cheers
Bennie