Union of two columns data into one column

Summary: We want to combine(Union) two columns into one column as shown in below screenshot. Country will be the new column which is union of Primary and secondary.

Content (required): We have two Columns Primary and Secondary Country, we want to present both columns data into one column. Union report is not an option as every time it is not feasible for users to create union report. So either in RPD and in Report criteria is there any option to union two columns into one column?

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