Merging Two Databases

I have two distinct mssql databases with identical schemas but different data on one system. I want to merge the data between the two databases by adding the data from one into the

Solution 1:

xSQL Software has developed a set of tools for this type of database operations. You can use xSQL Data Compare. To achieve the result you require you specify the left and right database, do the compare and then, to add the data that are missing from the left db to the right db you need to uncheck sync for the right rows and generate and execute the script.
Here you can see the rows unchecked:

And as you can see, the script does not generate any DELETE statements, only INSERTS for the rows that are missing on the right DB

Hope this helps!
Disclosure: I'm affiliated to xSQL Software