I've been finding the frame of brood that I want to graft from and putting it in my cell builder on the day before I plan to graft - then returning it to its original hive after I take the grafts. Last time I did this it rained on the intended graft day so that frame of eggs and brood spent about 36 hours in the cell builder before it went home.
This frame was solid with open brood and eggs on both sides.
Of course they had started raising a few queens on that frame - at that point they were just regular looking cells with a noticeably large dose of royal jelly in them - those larva seem to result in extra large grafted cells by the way, but that isn't the point of this thread.
When I return that frame to the hive with my pet queen is she likely to swarm or be superceded if I left one of those would-be queen cells on it?