How can I merge these entries such that ALL information from ALL fields is preserved and duplicate records are discarded?
How do you want to handle a case where there is conflicting information?
If there's conflicting information, I'd like to be able to visually compare the two (or more) records before deleting anything.
On which criteria do you define "conflicting"?
You could do something like this:
1. Define a self-join relationship of your Contacts table, matching on First Name, Last Name and E-mail Address.
2. For each field you wish to consolidate, define a calculation field (result is Text) =
List ( Contacts 2::SomeField )
3. Sort your records by First Name, Last Name and E-mail Address, and export them grouped by E-mail Address (exporting the calculation fields instead of the "real" fields).
4. Import the result to a new table, and review the results. Each consolidated field will contain a return-separated list of the original values. Some may be just duplicates - removing those would be more complicated.