Keep middle initial same for all kids? Opinions needed!

Hi! I have two DD's already and we are team green for #3. Naming our babies has always been stressful and put off until the last minute, so I am trying to get head of the game! 

So here is the dilemma. Both DD's have middle names that start with "I" and are nature themed- Ivy and Iris. Would it be weird if baby#3 does not have an "I" and/or nature themed middle name? Here are our ideas so far...IDEAS and SUGGESTIONS WELCOME and APPRECIATED! Thanks!

Esther Indigo
Esther Isla
Esther Magnolia
Esther Azalea
Esther Luna
Esther Irena

Lydia Irene
Lydia Isla

Moses Ignacy (Polish form of Ignatious-family name)
Moses Levi
Moses Ira
Moses Eugene (family name)

Solomon Ira
Solomon Eugene (family name)