MM MT202 FORMAT depending on Category

Hi Guys,
Would it be possible to have two different mappings for MT202 depending on the category of the MM.
For example, if it is 21075, we would like to have the Ordering Bank (CUSTOMER.ID) in field 52a, as sometimes we process loan transactions on behalf of Other banks, hence the need to have their BIC in field 52a.
If we have 21030 we would like to leave field 52a blank (instead of CUSTOMER.ID).
Do you have any idea how to achieve this?
Many thanks,

Hi,
You can achieve your requirement with same mapping.
Write a conversion routine where give the required logic based on your condition and attach same routine in corresponding DE.FORMAT.SWIFT record for the corresponding TAG.

Thanks for your reply. I will look at how to craft this conversion routine.
Many thanks,

Can you please help me start. I don't know what the arguments would be.