A couple things.....
1)If you put a box of foundationless frames above a full box of bees, and one box of foundation below the box of brood, the bees will almost ALWAYS draw the box above the already filled box. It is instinct that the bees start at the top and work down. It also has to do with the bees taking advantage of the trapped heat at the top, which makes drawing comb and other aspects of brood rearing much easier.
2) If you only place a box of foundationless above the brood chamber, especially when a heavy flow is happening, the bees may make honey storage cells, which may be in conflict with your desire to have them draw brood comb.
3) If you want to have the bees draw brood comb, the best place may be forcing them to draw comb below the existing brood chamber, like the features and benefits of the Warre hive protocol. Meaning the full brood box is placed on top and the bees have no place to build except below the existing box, and usually this will be worker cells.
You can also checkerboard in foundationless frames between existing drawn comb. But there are limitations early spring. And sometimes you get bulging of one side in the corners if the frames of existing comb has open nectar.
Much depends on seasonality timing, flow, what the bees desire and need, etc. And it comes down to what you are trying to achieve. Certainly the bees will draw comb by slapping on a foundationless box above the brood chamber. But it may not have the outcome of brood/natural/smaller cells that you originally wanted. You can't do what really comes down to "supering" with a box of foundationless frames above the brood chamber, and then expect not to have drone and honey storage sized cells.
I've been there, and done that...... ;)