Unpack a tar without creation of new directories, only merge new files from tar into existing directory structure

Question

Situation:

Lets mention there is a tar file with a structure like this:

• DIR A
  • FILE 1
• DIR B
  • FILE 2
• DIR C
  • FILE 3

And on my disk there is a directory with a structure like:

• DIR A
  • FILE 1
  • ... (more files and folders)
• DIR B
  • ... (files and folders, but not FILE 2)

Question:

Is there a way to achieve that the unpack command doesn't create new diretories (= directories which are not present in the unpack location shall be skipped/excluded) and that files which are already present won't get replaced?

After unpacking the disk structure should be like:

• DIR A
  • FILE 1 (NOT replaced by tar)
  • ... (more files and folders)
• DIR B
  • FILE 2 (from tar, because it wasn't there before)
  • ... (more files and folders, but not FILE 3)

(please note that DIR C should not be created)

Update

I already figured out that '--skip-old-files' achieves that old/existing files will not be replaced at unpacking.

Answer 1

for d in $(ls -d /home/bob/*/); do tar -x -k -f /tmp/test.tar  ${d}/* ; done

where $(ls -d /home/bob/*/) list only directories on your destination, -k preserve existing files