I have spoken to this a few times so I am sorry for repeating myself
I have been involved in three large and a bushel of small acquisitions during my business career. The following recipe was used in most acquisitions. When not used, what normally took two months for stores to get back to normal and start making money took years.
1/3 of the employees will jump on the band wagon day one. They are ecstatic that you took over their company.
Likewise, 1/3 will quit within +/- 30-days of inking the deal.
The last 1/3 will sit on the fence and see what happens. Some will get fired as they do not want to embrace their new owner's culture, direction, or rules.
What I would do about 60-days before the acquisition I would send in my District Managers to secret shop the competitors stores within their districts. Not to bore the reader they would look at how the store was ran using predetermined criteria. They would get a feel for how much or not, the manager was respected by the store's employees. Et cetera, et cetera, et cetera.
Once I got the DM's reports on each store manager, I put each store manager into one of the three boxes above. On day one of the acquisition, we terminated all the fence sitters. On the same day and for seven days the district manger would court the store managers that we knew would be happy with the acquisition. Send pizza to those stores, take the store manager out to breakfast, lunch, or dinner.
The last third will leave on their own as outlined, within +/- 30-days - Leave them alone.
Now let us look at the military, police, alphabet Stasi, et cetera.
1/3 will embrace the new regime.
1/3 will retire and go home to prepare for the Civil War.
1/3 will sit on the fence and fall on one side or the other over time.
Do you not think 'they' know where everybody falls when the hammer comes down?