Partitioning Struggles

I’ve just bought myself a new 2TB G drive mobile USB C for use on my mac.

I’ve created a 500GB partition to run my Time Machine backups on, and wish to create another (third) partition of 100GB to format as ExFAT to allow a small space to be windows-ready.

Disk utility however, is forcing me to split the remaining 1.5TB into two 750GB partitions rather than allowing a 1.4GB - 0.1GB ratio.

Is this a thing with partitioning or am I missing something here?

Cheers

You should be able to click the + to create a partition and then use the mouse to drag the lines to whatever size you wish.