You are asking 2 conceptually independent questions here.
- Can FTP, all by its little self, separate a file transfer into "groups"
No, it can't.
- Can an FTP client process more than one file at a time.
No, it can't. The client is basically a one process, one thread, function. A server, by definition, is a multiple thread function that can communicate with many FTP clients at a time.
There is no conceptual issue with running several FTP clients at a time all talking to a single FTP server.
I have tried, in the past, the equivalent of your idea, and it never seemed to work very well.
Breaking a large data transmission into "chunks" is not a bad idea, so that if there is a transmission problem with one "chunk" only the failing "chunk" needs to be rerun, not the entire transmission. In my experience, FTP on modern communication links rarely fails, so it's simply not worth the hassle.
In a past life I did customer support for a large ISV. From time to time our clients had to send us fairly large files. While we did have quite a few bad transmissions, it was almost always related to an error by the client. An example would be trying to send binary data as a text file, or sending a VB data set in binary. I don't recall any transfers aborted by a bad communication link. I was the local "expert" in trying to sort out these messes. About half the time, I was able to put humpty together. I could usually, for example, correctly deduce if a file represented SYS1.DUMPxx type data, or if it represented a file compacted by TRSMAIN or AMATERSE. My first two examples could not be corrected and had to be resent.