Is it possible to download and POST with multipart/form-data same file simultaneously, with libcurl?

Maybe this is a dumb question, given that I'm experimenting with libcurl, and also could be the case that is not possible to do. Let me describe you first the behavior that I want to achieve.

Suppose that I want to download some file, I could request this file by pieces until I get the whole file. Now, instead of storing this data into a temporary file, every time I got one of these pieces or chunk, I want to upload this piece to another server. Both servers are HTTP server, and the second one only accept the upload of the file, using a POST with multipart/form-data. I have an idea, but I couldn't make it work, and still not sure if it's possible. The idea that I had was to mimic the solution that I found in this question, but here they are doing it with the command line curl and the second server is an FTTP server.

So the idea is to create a pipe, and use this pipe to pass the pieces to the part that is responsible for the upload. Let's show you a sketch, in case you got lost in my poor English:

Maybe the pipe is not needed at all, because libcurl allows you to access these chunks of data, that you are downloading, like in the getinmemory example, but I don't know if it is possible to pass these pieces into a one multipart/form-data request, without storing the data into a file and later telling to libcurl to upload that file.

As I said before, I try to make this solution of the pipe work, but couldn't make it work. Let me show my incomplete code, so you get a concrete idea:

#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <curl/curl.h>

#define WE 1
#define RE 0



/*down_up video*/
CURLcode down_up(void)
{
  CURLcode ret;
  const char *url_down = "http://localhost:4000/static/videos/1.mp4";
  const char *url_up = "http://localhost:4000/upload";

  int pdf[2]; /*write end and read end*/

  if(pipe(pdf) == -1)
    errExit("pipe");

  pid_t pid = fork();
  switch(pid) {
  case -1:
    errExit("ok");
  case 0:
    /*closing unused WE in child proccess*/
    if(close(pdf[WE]) == -1)
      errExit("Close");
    break;
  default:
    /*parent process*/
    /*closing the RE on parent proccess*/
    if(close(pdf[RE]) == -1)
      errExit("Close");
    break;
  }

  switch(pid) {
  case -1:
    errExit("ok");
  case 0:
    /*child process*/
    CURL *curl_up;
    curl_up = curl_easy_init();
    curl_easy_setopt(curl_up, CURLOPT_URL, url_up);
   /*upload file with multipart/form-data, reading chunks from pipe*/

    break;
  default:
    /*parent process*/
    CURL *curl_down;
    curl_down = curl_easy_init();
    curl_easy_setopt(curl_down, CURLOPT_URL, url_down);
    /*download file, and writing pieces into the pipe*/

    break;
  }


  curl_easy_cleanup(curl_down);
  curl_easy_cleanup(curl_up);
  curl_down = NULL;
  curl_up = NULL;
  return ret;
}

int main(void)
{
  CURLcode ret;
  ret = download_upload();
  if(ret != CURLE_OK)
    return 1;
  return 0;
}

Here I'm trying to download with the parent process, and upload with the child process. In order to pass data from the parent to the child process, I close the Read end(RE) of the PIPE in the parent process, and close also the Write end(WE) of the PIPE in the child process. We get something like this:

But still don't know how to orchestrate all this. Is this even possible?