Populate field from parent table field

[Ryax]

I have a requirement to populate the Service Offering field on sc_task from the Service Offering field on the parent sc_req_item record. I was thinking of doing this as a business rule on the sc_task table. 

Is there a more appropriate way of creating this relationship or would a business rule be the most suitable approach?

[Uncle Rob]

Is this for a single Catalog Item or all Catalog Items?
I'd be suspicious of "ALL" catalog items as the sc_task teams could be rendering different subservices, and thus deserve their own field value.
Also consider... is the Service Offering known at the start?  Or does it change after creation?  If its known at the start just roll the population of the field into your Flow Designer flow.