Merging WhatsApp Stickers App & iMessage App

I am trying to modify the WhatsApp stickers app template released by WhatsApp on GitHub to include my own stickers. But apparently apple is against apps that only changed the content without much modification. My WhatsApp app had been rejected twice so far.

Is it possible to merge all the code from my WhatsApp stickers app to my existing iMessage sticker app? if yes how to go about doing it?
P.S. My iMessage App is already selling on the app store

If question1 is possible. Are the static variables from my main app accessible by my imessage extension as well after the merge?

Thank you so much:)