How to add more PKG installer packages into final installer file on MacOS?

[dominhhai]

I want to add a prebuild pkg installer package which will be installed on other directory with application directory.
How can I combine this pkg package into the final build as the following reference?
( If electron-builder do not support this combination, I have to combine by extra step )

https://stackoverflow.com/questions/38839054/how-to-combine-two-package-installer-files-pkg-to-one-big-combined-installer-f/38840657#38840657