What to do after minor accident?

My sister in law was in her car yesterday when the car in front,( to give way to another car ) reversed into her.
The reg plate and bumper were damaged,and the other driver apoligised and said he would pay for the reg plate to be replaced,he said he was distracted at the time.
My sister in law could see him reversing and flashed and blew the horn,now it was quite a hard bang.
Altough damage was miminal, to the car,she is unsure if she should tell the guards and see a doctor.
She had a 12 year old in the passenger seat,who is complaining of pains and has a headache herself.
I know that story of people claiming " compo " for no good reason.
However there are guinune storys of people suffering mussle spasms for many years after something like this.
What is the correct thing to do in these situations?

In any accident, regardless of the extent of any damage or injury, I would always phone the gardaí and get checked by a doctor.

They really should have called the Guards, at least then there will be a record of it. You can also make a report after the fact (happened to someone I know recently)

Make sure she and the passenger gets checked out by a doctor too, to be on the safe side as with any accident, the damage can be revealed at a later stage.

Absolutely, report it.
Quite a lot of insurance scams of this type happening, so be careful.
What the other party may claim on your insurance thay you drove into them, and are setting you up for a claim.
Generally, this is not the case, but cover yourself!

Just as a side note, a work colleague of mine was in a minor accident. Unsure of the damage to the car as I haven't seen it, but it was minor, perhaps scrapes and a small dent or such.

My 'friend' agreed not to call the Gardai, and the other driver gave his name and phone number. Needless to say my 'friend' is now mad because the number is disconnected, and he cannot find any trace of the other driver.

In saying that, when I first started driving, a car reversed into the rear side panel of my car. I was shocked, so agreed to take the drivers details, however I did insist on writing down his details from their insurance cert on their window, the policy number and name of the company. He gave me his name, address and phone number.

I called him with the quote to repair the damage, offered to send him a copy of it but he declined and I recieved a cheque in the post a day later.