There's a couple of possibilities with the queen cells. One is they are infected with a virus called black queen cell virus, which is found in the majority of beehives and from time to time kills queen larvae. If that happened you will find dark colored watery remains inside the cell. The other possibility is that the cells hatched, and afterwards the lids flipped back closed and the bees sealed them down again, which also happens reasonably commonly.
Based on the time frame you give, these cells are passed due date so you have nothing to lose by opening them to see what happened. Long as they are the same cells you sighted and left 15 days ago. If they contain dead larvae you will need to give a frame with eggs, if you remove from the other hive a frame with just a few eggs, it will not unduly tax the other hive as they will not have invested much into those eggs yet and can quickly replace. If the cells are capped but totally empty, that's the best outcome for you, the cells hatched but the lids were sealed back down, and you should have a virgin roaming around in the hive.
If in any doubt about anything, it never hurts to give a frame with some eggs, as insurance, and so you can if you want, take a look in a week and see what the bees are doing with those eggs.
Based on the time frame you give, these cells are passed due date so you have nothing to lose by opening them to see what happened. Long as they are the same cells you sighted and left 15 days ago. If they contain dead larvae you will need to give a frame with eggs, if you remove from the other hive a frame with just a few eggs, it will not unduly tax the other hive as they will not have invested much into those eggs yet and can quickly replace. If the cells are capped but totally empty, that's the best outcome for you, the cells hatched but the lids were sealed back down, and you should have a virgin roaming around in the hive.
If in any doubt about anything, it never hurts to give a frame with some eggs, as insurance, and so you can if you want, take a look in a week and see what the bees are doing with those eggs.
