Thank you for providing us with a picture of your requirements. It helped us to better understand what you need to achieve. Unfortunately, creating a RadDiagramConnector in the middle of a RadDiagramConnection is not possible.
However, you can achieve the same by using a customized RadDiagramShape. That shape will contain no geometry (or the geometry can define the look of a connection point), it will have small fixed size (e.g. 10x10 pixels) and will define only one connector in the middle. This will allow you to position the shape where you need to connect other connections and use that only connector.
We understand your requirement for connecting two RadDiagramShapes. Unfortunately, the RadDiagramConnectors are designed to be used in combination with RadDiagramConnections. This means that directly connecting two RadDiagramConnectors is not supported.
As for your second question, you cannot detect if two connectors are near one another, out of the box. The reason for that is the fact that the connectors of only one shape are visualized at a time.
Hence, in order to achieve your requirement you will need to implement big customizations into the RadDiagram.
One, possible approach which will be easier to achieve is that you can always connect two shapes that are positioned so that the space between them is less than 10 pixels.
Pavel R. Pavlov
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