The Merge button in navigators is used for both bulk editing of existing records and creating new ones. It is highly convenient when we have a list of records but we are not quite sure which of them have already been imported and which have not.
Until 2020.1 when merging records using the "Update existing records"option - we had to always add the full information of the record. When the system found the matching record, this record was simply deleted and replaced with the new one. This meant that we couldn’t really use the Merge button to update only some of the columns in the existing records.
In 2020.1 the Merge button updates only the columns which are shown in the View.
This means that if the system finds a matching record - it will only edit the fields that we are currently updating without losing the rest of the existing data. This allows us to effortlessly update columns of a list of records. For example, we can now easily аdd new Custom Property Values to a list of existing products.
I think the first part of the sentence "It is highly convenient when a list of records but we are not quite sure which have already been imported and which have not." is not fully completed. What comes after "when a list of records..." ?