What problem does this address?

For the Buttons Block (and eventually other blocks like List, Group, Column, Cover, Gallery), users might want to create patterns where all the nested blocks can be overridden, not just specific nested items. There should be a setting inside the parent block give users this option

What is your proposed solution?

• Add a "Allow overrides in all nested blocks" option for blocks that only accept one type of nested block like Buttons, List, and Gallery
• Add a "Allow overrides in nested blocks that support it" in blocks that can accept multiple types of blocks, like Group, Column and Cover.