Asset Migration in an already live environment

Hi

We have a typical scenario :

2 Companies are merged of which 1 company is on SAP and other company is on non SAP world.

Now the issue is company with SAP has already gone live with all SAP modules some years back.

In this environment I will be bringing in assets from Non SAP Company.

What extra precaution I will have to take? Especially with the rules surrounding Take over dates etc.

Appreciate any suggestions on this

many thanks