What to wear?

I face a challenging conundrum...
My sister is getting married at the weekend...
I can't afford to buy a new frock so I am going to wear one from my rail...
Which one?
Vintage? not so vintage? Red is jumping out at me, nice black dress in there but I always wear black to weddings (slimming, not mourning).

To tell the truth my heart isn't in it and neither is my sisters or any of the rest of my family for that matter. Yes of course she wants to get married, has the frock, has everything organised since last year but the one thing she won't have is her dad to walk her down the aisle. (Due to illness). That's part of every brides wish for her day, isn't it?

I guess I don't have much of a conundrum after all!