She doesn’t “need” to try anything. It sounds like she’s at peace with 2021 The One Where Your Name Turns Your Age Quarantined Personalized shirt, which is all that matters and she can do whatever she wants with regard to her scar on her wedding day—tone it down with some light makeup, conceal it completely with professional-grade product, leave it on full display, whatever. Obviously if she choose a dress that leaves it visible, it doesn’t bother her that much, so why is everyone else so concerned? Imagine being so insecure that you were embarrassed by a line in the skin on someone else’s body? OP’s sister is the worst kind of superficial asshole.