We have 7 developers in a team and need to double our development pace in a short period of time (around one month). I know there is a common sense rule that "if you hire more developers, you only lose in productivity for the first few months". The project is an e-commerce web service and has around 270K lines of code.
My idea for now is to divide the project in two more or less independent sub-projects and let the new team work on the smaller of the two sub-projects, while the current team works on the main project. Namely, the new team will work on checkout functionality, which will eventually become an independent web service in order to decrease coupling. This way, the new team works on a projects with only 100K lines of code.
My question is: will this approach help newbie developers to adapt easily to the new project? What are other ways to extend the development team rapidly without waiting two months until newbies start producing more software then bugs?