New Technical Business: Startup or Not??

After graduating from BITS Pilani, I have joined my family's manufacturing business and have plans for setting up a new enterprise also involved in manufacturing new technologies. I don't think I will require external funding for this project. Separate from our main firm, another company incorporated in 1996 already exists that is only involved in mutual fund investments. My question is if I should use that company for my new enterprise or incorporate a new one to avail startup benefits or doing in existing one will deprive me of other opportunities?