Dax advanced union type operation

Hi,
I am wondering if it is possible to perform a dax operation that does some sort of union of two tables and takes all the records from table1 but only takes the records from table 2 that dont have a matching KeyField value in table 1

E.g

Table 1
KeyField1, value
1 , London
2, Paris
3, Germany

Table 2
KeyField1, value
1, Sydney
4, New york

Unioned table
KeyField1, value
1 , London
2, Paris
3, Germany
4, New york

The record for Sydney is not included in the result because table 1 already has a record with the same key value of 1.


Thanks

James