OK, I've removed the bed. My daughters real oak bed now she's older and has a double bed in her room. This bed has to go now I can fit a single divan and I'm freestanding wardrobe with a 40cm cube with door going on top for storage. Satisfied?
Much better that than any attempt at using the backing board in a PAX to hold it to the wall.
The backs are often coming off over time as they are only fixed in place by a groove or some simple nails.
A totally unsuitable thing to use for support.
Assuming they are fairly standard, the fixing brackets screw to the chipboard sides of the wardrobe, not to the cardboard back. They then hook onto the kitchen cupboard style hangers. A kitchen wall cupboard loaded with crockery, tins, some pans, a food mixer stuck on top etc will weigh far more than that little wardrobe with kids clothes in it. If you want it on the wall, it's your fixings into the background that should be the determining factor, you could use a length of rail rather than 2 small hangars to spread the load and allow multiple fixings.