Check out some options how vcf files might be converted to npf format.
There doesn't seem to exist a way how you could directly convert VCF contacts to a Samsung NPF backup. However you can probably directly import VCF contacts or sync them with your Samsung device and perform the backup afterwards should you want it. Some older devices may accept only CSV instead VCF so you may try to convert that first using any of the available VCF to CSV conversion options.
Unfortunately, there is no detailed software record in the database for this conversion.
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