Hi SAP PI,
You have to decide a time interval after which file should be read by second sender channel. Target directory of first ICO (dir A) should be different than source directory of second ICO (dirB). Write a script which moves appended files from dirA to dirB after every 40 mins(say). It is possible that the script moves a file before it is completely written. Thus the script must check last modification time of the file being copied and compare to present time of the server. If there is some difference in timings then only it copies else it waits for a minute and checks again. Sender channel in second ICO picks up the file from dirB.
Regards
Anupam