[twohey]

I have experience doing this and am happy to talk offline as this is a complicated situation - just shoot me an email and I'll make time.

You will need to create organizational accountability for the integration and define what success looks like and how it will be measured. You will also want to avoid an "us vs them" situation inside the two companies.

There are a ton of subtleties in how to do that above that vary with organizational dynamics, but you must ensure that at a senior level you have alignment from both organizations or there will be a lot of shared misery.