You can’t make a silk purse out of a sows ear! Anyone else would see that space as a storage area and nothing more. My grandparents house was very similar and it was essentially an overflow of the loft!
It would be great as a shed, storage. Then they wouldn't have to waste space on the ship high decking with that ugly tin shed.
I don't understand why she doesn't just cull the toys and keep them to a minimum.
Those kids will not spend time in there. What a waste