Adding new field to BOL object

Hi Experts,

I have a requirement to add a field 'Middlename' in the BP search screen.

I am able to identify that, BOL 'BuilHeaderSearch' is associated with the model node. But, i am not sure from where the structure is sourced. ie, if it is sourced from BUT000, then the fieldname 'namemiddle' should be appearing when i try to 'create' the attribute. So, where should i search for mapping between an BOL object and corresponding structure ?

If there is no mapping defined, then how should i enhance/add a field to an existing BOL object ?

Any useful links/blogs will be helpful.

Thanks,

Gaurav.