This is very important for a proper relationship workflow for me and my team. The relationships currently leave a lot to the imagination or we have to document a lot so as why every link is important or what that link means or it's priority, etc.

Also using other custom fields is not sensible because of unspecified number of possible links and thus custom fields should be associated to every link.

Eg. use cases:

Name: Link Reason

Name: Dependency Type

Options:

Definition: Project cannot proceed without this

Example: Legal approval needed before launch

Definition: Required only under specific conditions

Example: iOS developer needed if building iPhone app

Definition: Would help but not critical

Example: Additional market research

These relationships could be visible similar to Rollups' visibility.