I was just asked by an older close family member (let's call her A) if I would be able to photoshop her stepdaughter (B) out of a wedding photo because she wanted to get the photo printed at a photo shop but only wants her 5 children in it. 
I'm not particularly close with my extended family at all and wasn't at the wedding myself, and I know there are other people A could have asked. On top of that A is always more than friendly towards B whenever I've seen them together, so I feel like I'm getting involved in something I don't want to get drawn into - A's child who's wedding it was is DEFINITELY going to notice that B is missing from the photo and will most likely kick up a fuss.
tl;dr - Even though I want nothing to do with my family, AIBU to say to my only close family member the somewhat upsetting news, that she will never stop talking about on the phone, that I don't have the skills to get rid of B from the photo?