You can add any number of data elements (both atomic, type-specific ones, and composite data structures) to any display element. The data contained in them will not be displayed to the end user, but can be set written and read as needed.
In the following screenshot, I've added several data elements (Some Number, A Data Structure, and A Database Record) to a Text Display, and while all can be accessed, only the <Value> element contents will be displayed to the user:
Reading/Writing of these elements, is the same as for the <Value> element, performed via a Display Data element (I guess this is what you mean in your reference to Change Display Element to Data Element) , which would look as follows:
Hope this answers your question, but if not please elaborate ...
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