Actually, early in the year or during a reasonable honey flow you can combine, shake or move bees around without much risk of fighting. If it is a fair day and they are flying you should have no problem combining frames of bees or even boxes of bees. I do it all the time without an issue. Remember the field bees are out and nurse bees are not going to fight so moving frames of bees is not a problem. Switching a weak hive with a strong one will cause the large field force to be lost to the weak hive. This can be of value when you have a strong hive wanting to swarm and a weak hive that needs a boost. The field bees will enter the hive and find a good queen laying on her brood pattern and leave her alone.
You don't need the paper but they will start mixing in minutes and have large patches open in several hours. A better and quicker method is to spray them with a squirt bottle of sugar syrup and scent such as anise oil. They will all smell the same and be unable to identify who is not part of the hive.