I would love for this feature to be added, there's no point adding complex "systems engineering" style issue types in a "Premium" subscription unless we can add multiple parents.
It's obvious that a Business Goal can be satisfied by multiple Business Requirements that much is already in the Jira software, but a Business Requirement can satisfy multiple Business Goals, and that ability is completely missing from Jira. The same applies to User Stories and Epics, throughout the entire hierarchy really.
I feel like this was a "we can't trust the users" situation, but its a roadblock for developing more complex systems with Jira as a planning and tracking tool.
Would be a great addition to my organization because of different phases of products but can link to multiple epics. this is mainly for code development planning.