We have had a very similar experience to you, not once but twice.
A few years ago we were about to go to Centre Parcs with the kids. Merc ML and Mark4 GTi in the garage. ML has roof box, and kids bikes in the boot, suitcases, cameras etc. Wife is breast feeding at 4am, hears the garage door and looks out the window to see the Golf reversing down the drive and then I hear the ML start up and that is gone too. There is a Land Cruiser parked at the end of my drive and it is full of blokes. They did 7 houses in the area that night. ( I live in rural Herts )They had taken the keys from downstairs. The ML had a tracker and that was found a week later in Enfield. The Golf was found in Luton 3 months later with a pound of heroine under the drivers seat, prompting another visit from the police to find out if I knew anything about that. The ML was fine but the locks had to be changed. The insurance company paid out on the Golf so I bought a Boxster. The family holiday to Centre Parcs was very stressful, we made it in the end in a hire car. No bikes, no money, no credit cards though.
3 months later my wife comes back from picking the kids up from school ( walking distance ) and the ML is gone again. This time they have broken in through the back, taken a sports bag and loaded that up with whatever would fit in. Even a bottle of champagne. This time the ML is found in Teddington. Locks changed again. I have taken the Boxster to the train station but they still take the spare keys so that has to have the locks changed ( £800 and a claim on insurance ). Second time we are hardened to it and go through the whole insurance process again.
What I can tell you is that your wife and kids will forget this over time.
Now we have an alarm with front and rear boxes, CCTV front and rear and always go through the same lock up process whenever we leave the house. Keys come upstairs at night.
But we don't take anything for granted anymore and are very suspicous of anyone we don't recognise walking up our road.
I hope it works out for you, sounds like your Golf is gone now though.
I have a DBP Mark6 GTi and it stays in the garage at night now. No tracker though as it is a company car.