Sync files - check if files exist in target folder and target sub folder

[snoopy2019]

Hello,

I have a source folder (A) with files.
I have a target folder (B) with 1 sub folder (C) which contains imported files.
I wish to perform the following sync:
Copy the files from the source folder (A) to the target folder (B)
if the files do not exists in both target folder (B) & sub folder (C).

How can I do it?

Thank you