how to merge a referenced table in a dataflow

[SANPERD]

Hello, I'm totally new on Fabric and I'm creating a dataflow.

Anyone knows why is not possible to create a merge with a referenced table? and what would be the workaround?

security table at left doesn't appear on the list for the merge.

Thank you so much for the answers.

[frithjof_v]

It's because it would throw a cyclic reference error.

You would get this error if you created that merge in Advanced editor:

Could you explain what end result you wish to achieve?

Can you do the merge the other way around - merging the legacy table into the security table? That worked for me when I tried. 

Or you can create a duplicate query and do the merge.

[lbendlin]

Do you really need to do the merge?  Can you do that later via the data model?