As a middle name, I'd say Suzanne. Jenna Suzanne.
As a sister, I'd say Rachel. Jenna and Rachel.
smith.
no cause Jenna is better expressly Jenna Boutilier
Jenna Giovanni goes by Jenna.
Jenna Mourey goes by Jenna Marbles.
sarah, jenna, lydia, or makayla
Jenna Ushkowitz goes by Crispy.
Jenna Nicole goes by Jennybean.
Jenna Coleman goes by Jen.
Jenna Gering goes by Jenn.
Jenna Golech goes by J.Go.
Jenna Lunarno goes by Jen.
Jenna Kanell goes by Sketchball.