For further credit and bank chain functionality difference ?

[PhanindraK]

Hello All, 

Can anyone explain me 
1. Difference between Bank chain functionality and For Further credit FFC functionality.
2. Can we modify DMEE file after this get generated from SAP and before reaching to the bank, since there is a middleware that collects DMEE file and make additions or further instructions to the banks and sends the file to bank.  Hope this happens after file saved in AL11 directory. 

Please clarify me on this and with SAP KBA to follow procedure . 

Thanks in advance.