how to give child image add fragment(overlay.conf) via VScode gui?

 I  use  the  vscode to creat a smp_svr sample project  ,and how can i easily add fragment to child image(mcuboot)?

as the picture1, the files overlay-bt.conf overlay-FOTA.conf both are serve to the main image "build_bt_1"

and the picture2 ,the pcd.conf and partition_manager_enable.conf  are serve to the child image “mcuboot”

where can i add fragment to the mcuboot  like picture1(edit build configuration -> kconfig fragments -> add fragment) 

Or can i use a special naming method (config macro or file name) in overlay.conf transfer it from the primary image to the sub image 

My expression may be vague,i just want to transfer config macro to child image  via add fragment