Contacts won’t let me add a new contact

I reviewed the thread that suggests using the “No Name” list at the end of your contacts as a workaround and that works but I will eventually run out of No Names. The second suggestion is to delete the “com.apple.AddressBook.plist” file, which apparently does not delete your contacts but only your preferences. The only issue I have with that is there are four “com.apple.AddressBook.plist” files in Library/Preferences on my MBP running Big Sur (11.7.10) and each has a string of seven different letters/numbers at the end of the four filenames. Three of the four files have “Zero bytes" while the other one has "2 KB" and all are old files. Should I delete all four files?