IDoc flat file to IDoc

I am receiving IDoc flat file in SFTP Server which needs to be posted into SAP. (No mapping involved)

What will be the best approach ?

1. I tried using IDOCFlatToXmlConvertor (The limitation is in the format of source file. The parent and child node relationship should explicitly mentioned in IDoc flat file which legacy system is not able to do) - Any workarounds ?

2. I moved the Idoc flat file into SAP application server. Now need to process it using scheduling a job for RSEINB00 program

3. File Content Conversion

Any other better solution ? Appreciate your help.

Thanks and regards,

Jose Augastine