External operation in routing

Hi

In routing if I maintain controlkey with external operation, I have to enter the info record details.

(I have to create info record without ref to material, the pur req/Pur ord created will be account assigned).

When ever I create an order the system will generate pur req for external opeation with ref to info record and it wil be always send to the vendor which i have maintained in info record.

My requirement is, I have 5 vendors who can do the same processing with different cost and lead time. I need to select the vendors.

Please let me know how to achieve this.

I cant go for Quota arrangement,since material number is not involved.

I dont want to create different routing with different info record details.

Regards

S.Senthil