The following is from Ask The VC, where Brad Feld and Jason Mendelson of Foundry Group answer questions related to venture capital investment and startups:
Q: How do I do multiple closings on a single round work? In our case, we have an investor wishing to give us headstart, certainly I imagine not an uncommon case in friend and family scenarios, though here we'd have multiple rounds of angels, without kicking up the gears to flush out a full seed round with other investors before that money changes hands.
Full Answer: http://www.thedeal.com/techconfidential/vc-ratings/ask-the-vc/how-do-i-do-multiple-closings.php