To relinquish her from her commitment

[Byebyebruno]

My SIL’s adult niece is a trained chef but stopped working at a restaurant as she wanted more flexibility.

I run a catering company and one of my usual staff is on holiday when we have a huge wedding.

Offered SIL’s niece the gig and paid her 50% upfront to secure her time.

Since then, she’s done bits and pieces of cooking for my events in the interim and I haven’t been impressed. Her food is great, the output is always fantastic, but her timekeeping and organisation are so bad. She doesn’t answer her phone, doesn’t show up on time, doesn’t answer email questions about the menu etc. It’s like she literally doesn’t give a shit. I’ve started to get sick of interacting with her. I can’t tell if it‘s pure disrespect or she’s just oblivious.

I want to find someone else to cook for the wedding. It’s a massive opportunity for us to impress a big crowd and she’s making me nervous, honestly. I know she’ll deliver in the end but she’s so unprofessional that the thought of it is stressing me out.

My friends are split 50/50 - half think I just fire her off the wedding, find someone else, cut my losses. The other 50% think I shouldn’t relinquish her from the commitment she made (particularly as I’ve paid her), and the only person to lose out if I fire her is me.

I could live without any drama too as we cross paths all the time at family stuff.

Have you said any of this to her or is she oblivious?

This.
Before you decide anything, you should of course start by raising the issue with her.
Of course it goes without saying that being punctual and responding to emails are very basic expectations. You can just gently pull her up on it and give her a chance to correct her behaviour. If she's a decent person she will, if not then you won't feel bad getting rid of her and if anyone in the family broaches the subject you can say "hand on heart" you gave her a chance and she blew it.

I have. I even offered her the chance to pay me back my deposit and I’d find someone else. She assured me she was committed and I didn’t need to worry.