Level of Effort for adding Ionic Side Menus

Hello all

I am not a developer but have recruited a dev company to create a Ionic app for us to run on iOS and Android. The app has about 60 pages and we are 90% done, but the arrangement now calls for adding a side bar menu item to the app which could be opened on all pages by hitting a button on the top navigation bar. Question is, the development company is saying they will need to touch all pages to add the side bar menu, but it seems like if we add the ionic side bar menu on the top page, it should take care of adding it to the child pages as well? Is that the right assumption or do all pages need to be altered to accommodate the side menu? I’m just double checking on the forum to make sure they are not overcharging us.

Appreciate any replies and advice!