Reservation for AAC u

Hello All,

we have a scenario wherein if the stock is available then we have to create the reservation in the back end system

Secondly if the stock is not available then we have to go for sourcing

My issue is when we are creating the reservation then the SC should not take the AAC U

if the stock is not available then it has to take the AAC U

can any one help me to configure this scenario

thanks

Srinivasa Chary