What width are the backing panels on the robe? Sounds like an old dodgy pantry we had where the back panel buckled - it had as much chance of keeping a large cockroach out as it does a small dog lol. So with the backing panel effectively useless, I would remove it completely & start over with the MDF interior wall lining in the above photo so it looks more like a genuine wall that was always there. I would paint the sheet prior to install ... I love these panels & the character they provide but those little grooves are pesky & time consuming to paint with a brush in situ. Best to spray paint it before it is screwed into place. I think it would look magic & at 9mm, should fit snug in your space? If money is no option, consider getting a pro in to rectify this & put the wall in.

i would invest in long term comfort and convenience and also raise the top shelf to create space for three levels of hanging space on one side, tall adjustable shelves or drawers with only enough space above the top shelf for suitcases and/or boxes of seasonal storage .. you need to design the space to suite the size and shape of what you need to store and a handyperson or carpenter could build in some of the diy wardrobe components like Multistore to help manage the space better or consider having a wardrobe company custom make the whole space to make life easier

I agree with Kate. This latest photo clearly shows that the top cupboards are too tall. The scotia or cornice will work on top sides of wardrobe, but at the moment, you can not put any joinery in front of the top cupboards because they will not open. You need, as mentioned before, to have the wardrobes reduced in height, for any installation to look good.

I am thinking of not walk in wardrobes but high quality wardrobes with various fixtures inside.