Attach Description of marketing program for free good

Dear gurus

In SAP SD standard, I can't find any field to type description of marketing Program for a free good record.

So I used internal order for this.

I create a internal order record to give ID and description of marketing Program. And when create a SO with have free good, I will give a suitable internal order in the Other field (AUFNR). So that I can get information into my report.

But this solution has a disadvantages in cross sales order. Because I can't select exactly internal order of company code A in Item because the different company code ( Sales org A belong to Company code A; Good issue plant B belong to Company code B).

Please give a solution for this.

Thanks

Manh Tuan