File Adapter : Sequence Check

Hello,

I'm facing the following issue: We receive files from a trade parter. These files have a sequence number in their file name. Eg. utilmd001.txt. We need to send these files as idocs to our SAP system. But we can only process a file if the previous file is already processed. Eg. utilmd003.txt can only be processed if utilmd002.txt is processed. Any idea on how to incorporate this in the file/FTP Adapter? Also note that we cannot assume that utilmd002.txt arrives before utilmd003.txt.

Any ideas?

Greetings,

Bart