Cannot use pre-git when node_modules is not in the same folder as .git folder

This is quite annoying: I have a project where the repo contains java back-end sources and the front-end sources in a separate folder, like so:

.
|____.git
|____project-backend
|____project-scripts
|____project-ui
| |____node_modules
| |____package.json
|____project-webapp

Is there any way to tell pre-git to look for package.json in a specific folder? If not can we add this feature? I'm up for it :-)