Sorry about the situation you are in. Are you absolutely stuck staying for a pension ? If not you have only 2 choices as my small mind sees things:
1 Drink the new company cool-aid and go all in .
2 Start the new job search TODAY !
Sucks, but you can't have things both ways , and trying to do so will be like sitting on a Pickett fence.
The exodus of your staff may be exactly the what upper management desires