Put a super under your standard brood box then another B.B.
Put the 14*12 in the bottom box with dummy boards each side.
Above that the same number of standard frames.
Feed and when the queen moves up add a QE. Keep feeding
When all worker brood has gone from below move the standard box to the floor. Add foundation as needed.
In other words a Bailey. You could put in an upper entrance if you wanted.
I doubt that they will put brace comb in the deeper floor space. If they do does it matter.
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