Intercompany billing - Exchange rate field open in VF01

Hello experts,

I have the need to open the 'Exchange rate-accntg' (VBRK-KURRF) field in VF01 header, for the Intercompany billing.

Today, the field is display only, while it should be open for modification.

Do you know if this is possible?

Thank you for any help.

Best regards,

JF