Car hit in NI - driver drove off

A friend had a small accident in NI - stationery NI reg car opened their door suddenly and my friend (Eire reg) hit it as they braked. The driver said sorry, their fault - they weren't looking - and then drove off!

My friend went to the local police as they had the car reg in regard to this other fella leaving the scene of an accident; the police said they knew the reg, and who the driver was, told my friend to go home and they would phone them later. Police said that they would not get involved, unless someone was hurt (they weren't) They did phone later and gave the name of the person driving, but not the address and said for my friend to contact their insurance with the name and car reg (though they also told my friend that they weren't the owner of the car!) They said they went round the drivers house and they said sorry for driving off, but they had someone sick that needed meds,and while the police were there, they rung their insurance (which is a bit odd if the car wasn't theirs?)

Now, the question is - does anyone know if Irish and NI insurance companies share details? I had thought not as NI companies are governed by the Data Protection Act? (Don't know about here?)

I just thought was it worth my friend phoning their insurance company here, and possibly losing their no claims, or just putting it down to experience and fixing the car themselves? (They actually had less damage, just a small dent to the side of the front wing and crack on the side of the front bumper - the other driver couldn't get their door closed)

I'd appreciate your thoughts?

Thank you