[Opinions] from what I heard...
Ginger Spice said she chose Bluebell because it was a pretty spring flower and her baby was born in springtime.
Neither Ginger Spice nor the little-known (at least in the US) movie short you mentioned would go very far to explain why two people supposedly chose Bluebell for sons. Although poor, poor, poor Bluebell Elvis, I'm willing to bet, was inspired by Bluebell Madonna Halliwell. SHAME on YOU, GINGER!