Creating a 'frames-like' environment.

I'm looking for a way to manage a larger program by using frames. What I'd ultimately like to do is have a high level VI that calls some other VIs based on some selections, but have the called lower level front panel VI load into a frame on the high level VI. The best analogy I could think of is like the old HTML frames. 

If it's easier, I could even load the called VI in a new window. It's not preferable, but it would definitely do if it's an easier solution.

Thanks in advance. Any help is greatly appreciated.