Not quite sure what kind of project you are talking about

But in general a project has many elements. The team leader is teh one who has teh overview of everything. If you can simply just give this new person one element and keep him/her busy with this one thing, then you will be OK to oversee the general picture. If your project involve customers then you have nothing to worry about. I assume that you have already built up good relationship with all yoru customers and a new person even if he is above you would not easily take that away.