Dual booting Mid 2012 MacBook Pro running Catalina with Deepin
It's quite straightforward, but when playing with partitions and dual boot systems, things can go wrong so:


First use CarbonCopyCloner to make a clone of your Mac in case anything goes awry.
Next, reboot the mac and hold down Command-R as it's restarting (when you here the gong usually) to boot into recovery mode.
Once recovery mode boots up, select Disk Utility and repartition the main disk (select the top disk (usually) and click the partition icon)
It will ask if you want to add a volume (which is what the 'data' volume is) or Partition, choose Partition.
Change the existing partition size to make room for the new one and Apply.


Now you have room for the Linux Boot Partition, simply follow the instructions at:

https://www.techonia.com/6156/install-manjaro-deepin-on-macbook-pro