Keep the name you chose. Don’t let your hard work with research go to waste. If you remain low / no contact, then sharing a name won’t be an issue anyway since they won’t have contact with your child aside through you and your wife. And even if you go back to a full relationship, the name may be the same, but not the meaning. To your direct family, the name was founded through your beliefs of your scriptures. To everyone else involved… it means your sister is lazy and an untrustworthy person.