Single iDOC to multiple files based on a condition

Hi Friends

need your help in one scenario which is something like this:

there is one iDOC as the sender and this iDOC has to be mapped to files based on a condition means let us say if there is a particular field "R" in iDOC than it should go and create the file "ABC"

and if the particlar field is P or G or M than it should create another 2 files named "XYZ" and "WUV" .

Please guide me how can i put this condition ?

Another thing in the same scenario is that i have to map one segment of the iDOC on its occurance to target fields.

Forex :

let us say E1WPB003 segment in the sent iDOC has only one occurance than it should be mapped to field ALT1

if this segment is repeated let us say 3 times

so the next occurance of the segment should go to the field ALT2 and next in ALT3 and so on.....

The max number of repeatation can be 9.

Please help me in this as i dont have any clue about how to go for this.

Do i have to make 2 DT 2 MT like that.....step by step things would be a favour.

Any help would be rewarded with points

Thanks