If I wanted to add bees to a weak hive could I: take a frame with brood and bees and insert it between two frames of bees in the weak hive?
Yes.
If you can switch hive locations and have bees fly into your weak hive thinking it is their home then it is not the "scent" of the hive that tiggers aggression and fighting. So this seems like it would work but I'm new to it.
Bees inside a hive are assumed to belong there, it is best to add the new frames to the brood nest. Adding a frame of eggs, larvae, and pupae, covered with nurse bees will assist a weak hive and there will be very little, if any, interactive agression between the new frame(s) and the other bees.
We discussed something similar in another thread but not this specific (between frames).
I had to add two frames of brood to a swarm I caught yesterday to get them to move down into the frames instead of the sides of the box and some bees that I did not shake off were still on the frames. They did not fight the new bees or viceversa.
The important part is here is
between the frames. Adding brood frames requires placing them in what is or will be the brood nest. Then acceptance is never a problem.
In Feb. I added a frame with bees above existing frames in a weak hive and they did fight but i added them above in a location the house bees had not had a frame in. Just experimenting in my mind. Thanks for any input.
The reason they fought in this situation was that the frames in a super, not the brood box so they were viewed as invading bees.
If you have several hives and want to do some swarm prevention management you can take a frame of brood and bees and put them all together in an new hive body and you will immediately have a strong split. Then replace the brood frame with an empty frame. Bees busy building comb in the brood nest usually won't swarm until after the brood nest is built back out. If you do this a few times each year you can often finese the bees through the swarm season without the hive issuing a swarm.