Adding .ipk file to build directure

Hi

I currently have a .ipk file i wise to add to my openwrt build directure. So i can built an image, upload it to a device and the .ipk/package are install on the device once booted.

I was think of making a new package in the package folder with a makefile, but i dont know where the makefile should install the .ipk file too, normally it is the source file which are installed from the makefile, which i dont have for this .ipk file.