Relation ship to prodcut and business partner

hi,

i have to find out the FM module to get the relationhip type of a product with business partner in service.

for example : in commpr01 there is tab called 'Relationships' under that partner sub tab is there.

there you can give BP number and relation type.

internally there should be FM to assign the product to a particular Business partner.

i need to find that particular FM which is updating these details.

so please help on this if any one aware of this.

thanks in advance.

thank you,

anil