Rehiving my box

I am new to this forum. Here is my sitstat. I recently 3/2 had my hive start to drop in numbers. Lots of honey in the super, capped brood with honey edges in the brood box with one full honey frame and one partial frame of honey. We looked for the queen and could not find her. Requeened. Hive continued to dwindle. Found the new queen dead only 200 hundred bees left. Cleaned the bottom board found no mites etc. Full honey super to freezer. Ordered a nuc. while waiting I notice hive activity, bees were robbing the brood box and had been for a week. Cleaned it again, wax pieces and dead bees. blocked entrance fully. I got my nuc and installed.
Good pollen flow starting . I think I am ripe for robbing. I blocked the entrance 1.5 inches. I helped my SIL with this hive for 5 years now on my own…