Cannot override some values in overlay-bt_hci_ipc.overlay using sysbuild such as CONFIG_HEAP_MEM_POOL_SIZE when building ipc_radio binary

When building ipc_radio under sysbuild, the order of the processing of the config files do not seem to allow me to override these values:

CONFIG_HEAP_MEM_POOL_SIZE=8192
CONFIG_MAIN_STACK_SIZE=2048
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
According to the build log this is the order of the config files:
Parsing C:/Users/david/ncs/v2.7.0/nrf/applications/ipc_radio/Kconfig
Loaded configuration 'C:/Clients/Client/Gen2/fw/boards/client/client_g2/client_g2_nrf5340_cpunet_defconfig'
Merged configuration 'C:/Clients/Client/Gen2/fw/gc_central/sysbuild/ipc_radio/prj.conf'
Merged configuration 'C:/Clients/Client/Gen2/fw/gc_central/sysbuild/ipc_radio/overlay-client.conf'
Merged configuration 'C:/Users/david/ncs/v2.7.0/nrf/applications/ipc_radio/overlay-bt_hci_ipc.conf'
Merged configuration 'C:/Clients/Client/Gen2/fw/gc_central/build/ipc_radio/zephyr/.config.sysbuild'
Configuration saved to 'C:/Clients/Client/Gen2/fw/gc_central/build/ipc_radio/zephyr/.config'
I also tried to add an extra config above "overlay-client.conf", but it still gets overriden with the above values in "overlay-bt_hci_ipc.conf"
I am trying to reduce the HEAP size to recover memory for other features, but so far this does not work, any suggestions?
Either those values should not be in "overlay-bt_hci_ipc.conf", or the order of the config files is incorrect?
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