Standard Cost recalculate during invoice

Hello Experts,

We person a pricing information with % for calculating the terms of Material arsenic Cost + Markup.
The contented which we person is, those Orders created during twelvemonth extremity mostly remains unfastened until adjacent year.
In the caller twelvemonth we person to tally Cost roll, truthful the modular outgo volition get changed. When Standard outgo changed, those unfastened Orders portion invoicing the Cost+Markup terms get changed since SAP billing ever recalculating the this Cost+Markup %. We acceptable Copy power for Item Category arsenic D (Copy pricing elements unchanged), but inactive it recalculate the worth during billing. Any thought this tin beryllium fixed utilizing modular config oregon we indispensable spell for enhancement.