You need to first up assess how full your supers are and how many brood frames are covered with brood at all stages.
Perhaps the best option could be a split straight away?
Looks like you have enough honey frames to get 2 nucs build up real quick.
Let them fill up 2 separate single brood boxes and pop the flow supers on top, once full. Extract the left over honey frames.
Spring is the time to do it. Don’t wait.
If I find the brood frames are full of brood at all stages, do I just split into two and wait for the new box to create it’s own queen? Then split the honey supers equally over each hive?
That’ll work as long as the both boxes have very very young brood: Eggs would be better.
If I decide not to split, where would you place the flow super. Top, middle or on top of the brood box. (see my diagram)
I answered (in detail) on the other thread where you posted the same question. 
You could go with the structure you have drawn above, however, it is not usual to have supers above or below the Flow super in a Flow hive. The reason is that supers are “extra honey”, not needed by the bees to survive the winter. They are usually therefore extracted by the beekeeper. If you put frames of honey above the Flow super, the bees may move them down into the Flow frames, or they may not. They are unpredictable and not trainable with this sort of thing. 
I don’t think you would kill the bees, but I would do something different. You will have 6 frames left over, if you follow your plan - what are you going to do with those?
Instead, I would suggest doing a kind of split, by taking 5 frames of brood from your existing hive, and putting those into the middle of the brood box of your Flow hive. I would put one frame of honey (if the frames are deep) on either side of the brood frames, against the hive wall, and one empty new frame in the remaining gap, between the honey frame and the brood nest, giving you 8 frames in the Flow brood box. If there are lots of bees and you put the queen into the Flow brood box, they should build up quickly and you could put the Flow super on top when the brood box is fully drawn and packed with bees.
The remaining hive could have a couple of frames of honey moved down into the brood box and empty frames to fill the gaps. They will make a new queen within a few weeks if you leave them a frame with eggs or very young larvae in it. You now have 2 viable hives, which is always better than having just one. 
so I wouldn’t need to buy a new queen?
If you follow Dawn’s suggestion on how to manage it you won’t have any need to buy a new queen and as she says you will end up with a second hive which is an excellent result.
cheers
You can buy a new queen if you want to have a mated queen to start laying right away. However, as long as the remaining bees have eggs or larvae which have hatched less than 3 days previously, they can make a new queen for you. Eggs are preferable, as it is quite hard to be sure that the larvae are less than 3 days from hatching (6 days from egg being laid). Figure 3 of this article shows an egg and a young larva (number 1 below it). Any bigger than this, and it is too late to become a queen.
It will be around a month before she starts laying, so you need to have enough bees in that hive to survive and forage until the new queen’s workers become available to help. 
Dawn, you said :-
You could go with the structure you have drawn above, however, it is not usual to have supers above or below the Flow super in a Flow hive. The reason is that supers are “extra honey”, not needed by the bees to survive the winter. They are usually therefore extracted by the beekeeper. If you put frames of honey above the Flow super, the bees may move them down into the Flow frames, or they may not. They are unpredictable and not trainable with this sort of thing.
What do you mean by the statement in bold italics? Should I put the flow super between the two traditional supers?
I mean that when you have a Flow super, you usually don’t need any other supers at all. Traditional beekeepers stack multiple supers because they often want to wait to extract until the end of the nectar flow. That is because traditional extraction methods are heavy, time-consuming and messy. It is more time-efficient to extract all frames in all supers at the same time. With the Flow super, you just empty a frame when it is full. You don’t have to take the hive apart to do it.
I wouldn’t. I would take the traditional supers off the hive completely and extract the honey. You only need the Flow super on your Flow hive.
The only reason I would ever put an empty traditional super on top of the Flow super is if they are being slow to cap the honey in the Flow super. The extra “head space” above the Flow super can help the bees to dry out the honey and finishing capping it. However, usually you don’t need to do this, as the bees cap it quite happily.
I would never put a full traditional super of honey onto a Flow hive. There is no reason to do so.
Hope that is a bit clearer.
Ok. thanks Dawn. I understand your comment.
The reason I want both types is that I like
the idea or producing honey comb, great on blue cheese and for gifts, simple wax candles, etc… and pure honey via flowframes.
I want the best of both worlds 
I could have separate hives, but have limited space at home for two. So am
thinking of a hybrid
Hiya Dave I have a couple of hybrids and have had success although there are a few drawbacks. The bees do prefer drawing and filling the outside standard frames. Not giving this option with a full Flow forces the bees to accept the Flow frames and produces higher yields.
It is pretty cool watching them draw out the frames through the side window though.
On Sunday we crushed and strained last seasons frames. They seem to accumulate and the cursed moth is out and about and no freezer space… It’s straining now and a mess still to clean and wax to render… We extracted one of the hybrids the same day, (The full standard frames were swapped out the previous week.) it was all done in a couple of hours, just shy 10kgs, too easy. 
That is the disadvantage of a Flow Super, you don’t get any wax.
Bite the bullet and fit in a traditional hive somehow, a second hive has so many advantages with hive manipulation and replacing of a queen when one is needed.
cheers
we are finding that we almost need to add extra ideals (half depth supers) to our one brood flow hives- as otherwise they quickly become pretty crowded and could think to swarm. I think you can get aawy with just a single flow super if you split and/or requeen your hive annually. My mothers flow hive is currently so massively populated I was considering adding a second ideal. As is we just harvested the one that’s there and replaced the empty frames. I’m hoping that will keep them busy for the moment. Touch wood. At least that’s how things are going here in adelaide with our long honey seasons.
Mum’s hive had only a flow super for the first few seasons: but qwe did take spring splits off it each year to slow down the spring build up. This year I didn’t split and the numbers of bees have been prodigious.