1. Anyway you need to find and note all the places where is editReferenceField used. Because you need to test all these places later;
2. Then check and note all methods editReferenceField.???;
3. Create the new functional component below and export all the props from p.2 window.editReferenceField = { someFunc: theFunc, otherFunc: theOtherFunc };
4. One by one replace and test all components from p.1. If something wrong, use the class component to compare and note the difference, resolve them;
5. Finally test all the places from p.1;
6. Remove class component.

If it's impossible, then just don't touch it for now.