Adding new items to a structure

I am trying to add new items to a structure I created, but it seems to fail. I created a cell initial and each cell has a structure. I am trying to add more items to the structure in each cell, without affecting the existing content. Attached please find the .oml file which shows how I generate the structure and how I am trying to add a new item to it. It works most of the time, but when I try to clear the workspace Compose crashes. Is my implementation correct?

Thank you

Berker Bilgin

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