Yocto: Can't install recipe into a non-standard directory - directory

Question

The task:
Our system has a readonly rootfs so I need to modify the NetworkManager directories to links that point to a readwrite directory, otherwise it doesn't work right.
The problem:
The chosen installation directory for some files is not present on the image.
Using "/data" as the install directory, which is mounted using fstab from another partition:
/dev/root / auto ro 1 0
/dev/emmcp2 /data ext4 defaults 0 0
and is added to base-files package:
do_install_append() {
install -d ${D}/data
}
FILES_${PN} += "/data"
During the build process, "/data/NetworkManager" and the other subdirectories bellow appear in the pre-packaged directory (so install command seems to work fine).
After build finishes, it is missing "do_populate_sysroot" step BUT it does have the "/data" directory in "build/tmp/sysroots-components/"
If I use "/home/root" as the installation directory, everything is fine. There is a do_populate_sysroot step and when booting the image all the needed files are present.
The bbappend recipe:
FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
SRC_URI_append = " \
file://NetworkManager.conf \
"
# Current path in install directory
PATH_PKG = "${D}${sysconfdir}/NetworkManager"
# New path in install directory
NEW_PATH_PKG = "${D}/data/NetworkManager"
# New path on target
NEW_PATH_ROOTFS = "/data/NetworkManager"
FILES_${PN}_append = " \
${NEW_PATH_ROOTFS} \
"
FILES_${PN}-cloud-setup = " \
${NEW_PATH_ROOTFS} \
"
# This variable contains directories that are installed by default
##### Adding this doesn't seem to do anything
SYSROOT_DIRS += "/data/NetworkManager"
# The package needs to be moved to a readwrite location.
do_install_append() {
echo "### NetworkManager bbappend installation START ###"
echo "\n"
echo "Current NetworkManager path = ${PATH_PKG}"
echo "New NetworkManager path = ${NEW_PATH_ROOTFS}"
# Remove existing directories:
rm -rfv ${PATH_PKG}/conf.d
rm -rfv ${PATH_PKG}/dispatcher.d
rm -rfv ${PATH_PKG}/VPN
rm -rfv ${PATH_PKG}/system-connections
# Create end-point folders
install -dv ${NEW_PATH_PKG}/conf.d
install -dv ${NEW_PATH_PKG}/dispatcher.d/pre-down.d
install -dv ${NEW_PATH_PKG}/dispatcher.d/pre-up.d
install -dv ${NEW_PATH_PKG}/dispatcher.d/no-wait.d
install -dv ${NEW_PATH_PKG}/VPN
install -dv ${NEW_PATH_PKG}/system-connections
# Create symlink for common directory
ln -sv ${NEW_PATH_ROOTFS}/conf.d ${PATH_PKG}/conf.d
ln -sv ${NEW_PATH_ROOTFS}/dispatcher.d ${PATH_PKG}/dispatcher.d
ln -sv ${NEW_PATH_ROOTFS}/VPN ${PATH_PKG}/VPN
ln -sv ${NEW_PATH_ROOTFS}/system-connections ${PATH_PKG}/system-connections
# Add custom configuration for Network Manager
install -v -m 0755 ${WORKDIR}/NetworkManager.conf ${NEW_PATH_PKG}
ln -sv ${NEW_PATH_ROOTFS}/NetworkManager.conf ${PATH_PKG}/NetworkManager.conf
echo "### NetworkManager bbappend installation FINISH ###"
echo "\n"
}
I thought SYSROOT_DIRS was the issue but unfortunately not in this case. Maybe someone has an idea what else I could try?

Answer 1

So I wasn't able to determine the exact cause but found an alternative - "volatile_binds" image feature.
It allows to sort-of overlay a writeable location (I chose tmpfs), on top of a read-only directory.
The best thing is that it is package-agnostic.