If the good Dr will give me a chance...
I use a starter box to get the grafts accepted.
They are then moved to a strong colony to finish and if required the starter box is used again.
In the strong colony they are put in a populous super which to my mind must be the top one so as to get the cells as far from the queen as possible to avoid upset. They are left there until sealed, and after that put into cages in case of mishap to the beekeeper.
Always plan for the worst (motor malfunction, life issues, etc) and with the cells in cages the virgins will be fed and cleaned. So still useful for mini nucs.
Or of course the sealed cells can be put into nucs.
PH