First things first. Consult with an attorney and an accountant experienced in the creation and representation of private investment funds. Do that to get familiar with the issues you'll be facing--even before you start talking to consultants.

As with the formation and running of other kinds of businesses, you have a number of considerations gong on here: the need for limited liability protection (which your current general partnership status does not provide), tax issues (the treatment of which vary depending on the entity you choose), financial issues (the costs of perhaps forming separate companies for each subsidiary), and other interdisciplinary legal issues that may touch on U.S. and international taxation, banking regulations, the Investment Company Act and other securities laws.

In addition, you will have management issues that must be dealt with in some form of entity ownership agreement (among other investor-related documents). For example, what if Subsidiary #1 doesn’t perform as well as Subsidiary #2? Are all of the members willing to take the loss? Are you adequately disclosing these risks to new potential investors?

Make sure to get advice that’s tailored to your situation--this is definitely an area where you do NOT want to rely on what you find on the internet alone.