Merging databases with identical schema
I have had this problem. Sometimes I have had to solve it the hard way. But others I simply take a large enough number and add it to ALL the numeric keys in one of the databases. Then I merge the two databases.
Let's say if my biggest key in BD1 is 1213456, I add 1000000 to all the keys in BD2.
You can prepare your scripts querying information_schema to generate all modifications/alterations/updates. Something like (only PK)
SELECT CONCAT('UPDATE ', U.TABLE_SCHEMA,'.', U.TABLE_NAME, ' SET ', U.COLUMN_NAME, ' = ',U.COLUMN_NAME,' + 100000' )
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS    C
    JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE U 
        ON U.CONSTRAINT_NAME = C.CONSTRAINT_NAME
           AND U.CONSTRAINT_SCHEMA = C.CONSTRAINT_SCHEMA
           AND U.CONSTRAINT_NAME = C.CONSTRAINT_NAME
WHERE C.CONSTRAINT_TYPE = 'PRIMARY KEY'

Will return queries like UPDATE dbo.Table1 SET id = id + 100000
And running results queries when you feel confident enough. Good luck!