One of the hives we were certain the queen was placed into the new split, but for the other hive we couldn't find the queen so unsure what half she is in.
Hi Phil
To find out which half the queen is in, simply place the two boxes 20 feet or so apart, and away from the old stand (so that returning foragers don't confuse the issue). After about 20 minutes, you'll notice that one box will have become far more distressed than the other. That's the queenless box.
Best practice is to then place the box containing the queen on the new stand. With a laying queen, that colony is viable, but will be forager-free for a few days, until some older nurse bees become 'promoted' a little earlier than usual. Although forager-class bees will certainly return 'home', no other bees will abscond with a laying queen in the box.
In contrast, the queenless half is potentially in trouble (assuming a walk-away split), so it's placed on the old stand precisely in order that the older forager bees (which are an extremely valuable resource) will continue to swell the numbers, as well as bring in forage. There's no reason for any bees in that box to 'return home', as they're already there !
However, if you make multiple, rather than equal splits, one or more of those boxes will be located away from the old stand. Simplest measure then is to seal the boxes for a couple of days, ensuring that they have ventilation and water (or even weak syrup). Because those boxes are sealed, they can then be placed anywhere cool, such as a cellar or in the shade for that period of time. Return them to their new stands before opening them up, of course ...
LJ