you can strap them and/or use staples to hold them together. you can buy hive staples, but the bigger electrical staples work also. close the hive up before hammering
. to close fronts, i use an entrance reducer held in place with duct tape. it's easy and keeps bees from sticking to the tape.
since you have to move them, it doesn't matter whether it's safe or not
. i don't see any problem with it. they will be fine when the weather warms up and they start flying.