Firstly so sorry about the loss of your sister 
I love Evangeline she’s elegant, romantic, whimsy and ethereal. A beautiful name that is connected to Angela through ‘angel’ however I wouldn’t say the connection is very obvious one. I think choice like Angelica or Angeline would be a more obvious choice. Still I think honour names are complicated and the plus point of Evangeline is that the name is separate enough to give her own space/name identity as @EloiseT mentioned. So in a nutshell I think Evangeline is a great idea even if the connection isn’t overtly obvious.