The ability to re-arrange the information on the related tab would be very useful. Linked records can grow incredibly long. Having other fields at the top would be incredibly useful.
Thank you for your idea. It is currently possible to rearrange the order of tabs within the custom layout. This article explains in more detail: https://www.aha.io/support/suite/suite/customizations/custom-layouts#adjust-layout-tabs
Given this capability, I am going to adjust the details of this idea to focus on your second suggestion of customizing the Related tab. Thanks!