Do bulbing bunching onions multiply like non-bulbing ones and potato onions, do?
According to one source, there is a non-bulbing variety that does multiply (and is a perennial): the He Shi Ko bunching onion. I have yet to find such a source about bulbing types.
High Mowing Seeds establishes that bunching onions (not particularly bulbing ones) are hardy perennials that are for some reason usually grown as annuals, but it does not say if or how often they generally multiply.
Another source says that technically the non-bulbing ones are bienniels, but people often refer to them as perennials because they multiply, leaving a continual supply. So, are the bulbing ones the same in these regards?