Override HMC.xml type configuration

Hi ,

I am trying to override a type in the hmc.xml of HMC extension in my core extension . But it doesn't override instead it creates the duplicate of it in the final hmc.xml. It looks something like this.

Tag in the hmc.xml of HMC extension

type name="BusinessProcess" useselector="true" mode="append"

Tag in the hmc.xml of Core extension

type name="BusinessProcess" useselector="false"

HMC is extension is visible in my core extension Can anybody suggest ?