Need suggestions on XI Design

Hi Experts,

My scenario is File to IDoc. I will be getting different files (ex: file_a.csv, file_b.csv, file_c.csv, file_d.csv) from legacy system. I am having 4 message types in ECC. If I get file name as file_a.csv then I need to map with one message type. If I get file name as file_b.csv then I need to map with another message type. Like this I need to map different files with corresponding message types. But Receiver is the same ECC. This total requirement is in one Interface only not different interfaces.

How do I desgin this scenario.

Need suggestions from all experts...

Regards,

Rams.