Down payment SD in Contract

Hello,

I have just set up a process in our system to manage customer down payments.

I followed the following blog: Down-Payment Process without billing plan in SAP

Our need is to manage the down payments from the contracts. so I put AZWA and AZWB in the contract pricing scheme, but AZWA is not displayed on the contract and on the order it is not modifiable.

on this blog : Several points need to know when using condition-based down payment, the author said that AZWA is not scheduled for contracts (VBTYP = G).

So how can I activate it for contracts (VBTYP = G) ?

Many thanks.