Default path for bblayer.conf
build_xwayland/conf/bblayer.conf
bblayer.conf file is used to add extra layers. e.g to add meta-poky layer in image add following line in bblayer.conf file
${BSPDIR}/sources/poky/meta-poky \
Layers can also be added using bitbake command
$ bitbake-layers add-layer <path of the layer>