It's not in your interest to have them join the same round. The valuation YC invests at would be a bad one if we were only supplying money. So what we'd recom

It's not in your interest to have them join the same round. The valuation YC invests at would be a bad one if we were only supplying money. So what we'd recommend is doing another round after YC's at a higher valuation. If you were in YC we'd obviously help you arrange that. Your call whether you want to take the money during YC or have your potential investors come to Demo Day with everyone else (assuming they don't already).