Falg Measure to activate inactive relationship between two tables

Hello
I have 2 tables (tableA and tableB) related with inactive relationship. I want to create a flag measure that activate the relationship between tables. 
I want to be able to chose an attribute from one table and see relataed attribute from the other table.
I begin with doing this measure and I want to know if it is the better solution :
PS : tableA is the many side of the relation

CALCULATE(
	SUMX('tableA', 1),
	USERELATIONSHIP('tableA'[FkI_tableB], 'tableB'[ID_tableB])
)