While placing family instances, it deletes one instance already placed

[SeanP]

Read this.

Element Binding in Revit

Element binding is the name given to the process which Dynamo manage to ‘track’ the items created in non-Dynamo files. In this case, I’m going to focus entirely on element binding as it refers to Dynamo for Revit, but the mechanism exists to allow for this behavior in other applications (advanced steel, fusion, alias, etc.) as well. In the context of Revit, ‘elements’ refers to anything with an Element ID in the Revit database. When utilized correctly, element binding will expand how you leverag…