New event to customize clearing unmerged merge fields during mail merge Completed

Finalized requirement: 
New event to trigger before clearing each unmerged merge fields during mail merge execution.

Event arguments should have properties,

1. To hold group name of a merge field

2. To detect the reason for a merge field to remain unmerged 
      2.1. doesn’t have mapping field in data source
      2.2. has mapping field in data source, but the data is null or string.Empty
3. To update unmerged merge field with exception text

Initial query: "MergeField is not replace/removed if value is null"
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We use mergefield in a document template, these fields are related to variables that user can fill or not in our application. If the user doesn't fill related cell in application grid, when document is generated by replacing mergefield -> as value is null, the mergefield is kept inside the output document.

We need a way to have that mergefield removed when replacing, otherwise we'll have not suitable output

Template                                  Output  

Name: «Text:FUNCTION_DESC»    ->     Name: «Text:FUNCTION_DESC»      Current behaviour

Name: «Text:FUNCTION_DESC»    ->     Name:                                                  Desired behaviour

Is there a way to perform this management ? The same behaviour is desired both for mergefields inside a group and mergefields at document level

Thanks a lot in advance for any helpBest regards

Giacomo
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