Change the height of the Relationships/bottom part of a form with relationships

Hello,

I'd like to give more space to relationships for a Form with few Item data but lots of Relationships data. Taking the standard "Document" Form as an example, I'm OK with the room available for attributes but would like to give more vertical space to Files and Changes.

Customizing the Height of the form only adjusts the Item/top part of a form, not the Relationships/bottom part. Do you know any way to change it?

Thanks!