I'm trying to backup and restore a 64 GB iPad Pro (2017) to a 32 GB iPad Pro (2016). I removed enough data from the 2017 iPad to make it use only 26 GB of the 64 GB. But when I try to restore it to the 32 GB iPad it doesn't work complaining that there is not enough space on the iPad. How is this possible? Btw I should also say that the content of the 64 GB iPad Pro is itself the restored backup from an older iPad Air 2 which had about 46 GB on it. But for some reason I still don't understand that shrank to 26 GB when transferred to the 64 GB 2017 iPad Pro. What's going on here? Could it be (just wildly guessing) that the 20 GB of missing data from the iPad Air 2 are hiding somewhere on the 64 GB 2017 iPad Pro, as well as its iTunes backup, and that is why the backup can't be transferred to the 32 GB iPad Pro?