The best tool to split a large vCard file into multiple or to merge many vCard files into one is the Aryson vCard splitter and merger. This software is virus free and lets you split or merge your file without any data loss. It maintains the contact information after splitting or merging the vCard files. It supports the vCard files created by different platforms. The demo version lets you merge or split 15 vCard/VCF files for free.

https://www.arysontechnologies.com/vcard-splitter-merger/

Look at the easy steps on how you can set up the software:

Step 1: Download and run the Aryson vCard splitter and merger tool.
Step 2: Add the vCard files by selecting Add files or Add folder.
Step 3: Select the vCard files and choose the destination path.
Step 4: Choose the Split or Merge option.