Honestly, I agree with you. It's you and your partner choice to name your baby because you and your partner made/adopted him or her, not your parents or your in-laws or your friends.
What I would say if somebody says:
"Oh you should name your baby Adain/Jessie/Cookie!"
You should say:
"That might be a good name for our baby" and then DROP THE SUBJECT!
Or
"Thanks for the imput. We'll consider that" even if you don't want to consider it at all.
Because if you say:
"Well I'm thinking that's not such a good choice..."
Your friend/in-law/ mom will go on and on defending why Adain/Jessie/Cookie is the best name for your baby when it's not even their baby!
Just thank them for their imput and drop the subject.
I really hope that helps Waiting for #2!

Congrats on your second one!