1. Update the review step to compare (Review stage):
User field values.
Find supported fields.
Update logic to display user-readable values for fields
Entities where user is referenced
Entities that user has authored
2. Update the review step to add the following option (Choosing values stage):
Choose one of the values from both entity (These will result in auto-updating the chosen value without any further user intervention)
Merge values (These will result in using both values without any further user intervention)
Merge and edit values (this will allow user to do more picky merging, later in the process. User will be able to change values, choose/discard values in case of multi-value fields etc.) (Also, this is the most expensive step in terms of the efforts needed)
Write plugin/form handler to handle this for various kinds of field user entity has (text, links, paragraphs, entity references etc.)
Write plugin/form handler to handle this for entities where user is referenced
Write plugin/form handler to handle this for user authored content
3. Add/update merge logic (Actual merging stage):
Update the existing following logics to update based on choices made in the above step:
basic fields
entity reference
reverse entity reference
authored content
Add the merge logic (based on choices in last step) for fields/cases not already covered by module: