Custom connector in Draw for a value stream map


I’d like to create a value stream map in LibreOffice Draw. To illustrate the electronic infomation flow it is necessary to use a connector shaped like a bolt (see the picture)

I tried to use the line connector. By pulling the points of the connector you are able to form the connector in a way that it looks like a bolt. But you can not pulling the linked shapes without loosing the bolt shape.
Is it possible to define a custom connector? Or does somebody know if there are plugins available for value stream mapping?

Thanks a lot.