Go with what you have selected -- those prints are similar in design to her picture and look lovely. She probably doesn't have enough experience to be opinionated at this point. However, she will definitely have an opinion when it is finished. Keep it simple to reduce the investment of time on your part. Whatever happens, you will have to be gracious about it, keeping in mind that the road ahead for your sister with this new person in the family may be a bumpy one and she will appreciate your support.
Dayle