multiple source structures and send to 2 text files (Complex)

HI Friends,

I got complex scenario.

My Source system having multiple type of XML files there i need to select three types of files only( max_ receiving file , bex_receiving file and Returns file)

Here Max & Bex having same structure and return having different structure.

client want pick three XML files and send to 2 text file to different folders into Target

Here No merging conditions and splitting condition.

In mapping field one field like this If get max and bex files picks the field value add "D" prefix of the value( ex D12345)

returns file picks the field values add "R" prefix of the value(ex R4567)

Example:

Target

file structures

total

Header

.....

........

Body

MAX&Bex Filed1

filed1 Filed2

field 2 Field3

field 3

Trailer

Returns Details

Header

Body

Field1 Field4

Field2 Field5

Field3 Field6

Field4

Field5 Trailer

when ever pick the MAX file from source use max values send to total and details

when ever pick the Bex file from source and use Bex values for total and details

when ever pick the Returns file from Surce use return values for total and detais

Mapping like this

For MAX ,Bex AND Returns for total

Field1 to field1

Field2 to Field2

Field3 to Field3

For MAX, BEX & Returns for Details

Field1 to field4

Field2 to field5

Field3 to Field6

Out put

Total

Header

some fields here

BODY

Field1 Field2 field3

D123 aaaa bbb

D456 ccccc bbbbb

D125 xxxx ddddd

R111 zzzz fffff

R145 ssss kkkk

Trailer

Field1 field2( no.of body records)

Details

Header

some fields here

Field4 Field5 field6( field names are different in total and details)

BODY

D123 aaaa bbb

D856 ccccc bbbbb

D345 xxxx ddddd

R789 zzzz fffff

R100 ssss kkkk

Trailer

Field 1 field 2( no.of body records)

So please guys tell me how can i solve this problem step by step.

Its very Urgent.