Re: Robbing Activity after Split?
Could be nothing but orientation flights. Did it occur in the late afternoon? Robbing generally will go on until dark if you do not close off the hive. Regardless, you should have an entrance reducer set to the small opening in place on a walkaway split, or a robbing sceen. It will be about four weeks before you have any new bees to defend the hive after this bit of brood emerges.
When you go into the hive, ragged edges on the comb of the honey frame would be a potential sign of robbing. That and dead bees. Check to see that a queen cell or two have been started. Probably won't be capped yet, but clearly identifiable. Not much else you can do at this point.
Thankfully, the bees are smarter than I am. They are doing well, in spite of my efforts to help them.