Guest RC, are you sure about that? I thought "Robyn" as a female name was a fairly recent usage emanating from the USA. Spellings in medieval times were not fixed, and the use of the y spelling is probably not significant - "Robyn Hood" is sometimes spelt thus in old documents.It started out as a diminutive of Robert, eventually becoming a name in its own right. I have never heard of the Virgin Mary being addressed as Robyn.

It makes more sense to regard that line, in the vernacular, as an aside from the mother asking a male (husband, son) to stop pestering the baby.

Marje