Cannot RePartition Cannot Erase on Mac

WD 4TB My Book Desktop External Hard Drive So I am on a MacPro 2013 with the latest OS. I have partitioned this drive into 4 partitions. I was trying to enlarge the drive I use for my home identity backup, and had too much space on another partition I was not using, but when I tried to repartition, it creates another partition called Unknown and I cannot add the extra space to the backup. When I look at it in Drive Utility, it says it is in a separate container on the same 4T, so I am confused. I have tried to add the extra to the backup but it only lets me add it to other partitions and not my backup. As a last resort, I tried initializing and erasing the entire 4T but I cannot do that either. It is like locked somehow. If I could just add the extra space I created in Unknown to the backup, that would be great but cannot.