Grandson (12) stealing something from my bag then lying about it

I would cook the steak. I'd forget about the chocolate. It might be a good idea to start treating him a bit differently to his younger siblings-so perhaps give him the chocolate when you arrive and say "It's up to you when you eat it, I'm saving the others till such a time." He's at the age when he wants control of something and giving him some choices might help. I wouldn't tell his parents, but I would tell him that you aren't going to tell anyone this time but you might have to if it happened again. He does need to know that although he is older you all still love him. Older children sometimes think they don't have the charm of their younger siblings.

But perhaps no chocolate on Saturday; if he asks why tell him he had double doses already.

No-one goes in my handbag, not even DH. He says there's a crocodile in there.

I agree with Bridgeit and other posters.
I think it's best dealt with between the two of you.
And cook him his steak

If I was in your place, I would cook the steak because I feel consequences should attach to the infraction and not pop up elsewhere. I'd also drop the subject of the chocolate, as was promised, but not bring any the next time I visited. Then, if the kids asked about it, I'd nonchalantly mention (without not focusing my gaze on anyone in particular) that I wouldn't be bringing any for a time because I was a bit sad that some had been taken from your my purse during the previous visit.

Definitely give him his steak dinner.

Oh God! Don't pile a load of guilt on him for that! Why didn't you just call him a little bugger and tell him no choc for him next time? And then forget about it when next time comes around.

I always take choccie for my two. If I catch one sneaking a bit of the other one's they get yelled at.

Why didn't you give the choc to them straight after lunch?

Let it go on this occasion and don’t tease the children that way.

“Thou shalt not tempt”

I would go ahead with the steak meal.
You are seeking to help him Change his behaviour so better to chat over the steak on the lines of ‘ I.m so glad we got that out in the open , & that we can trust each other to talk about things that are troubling us etc
He needs to have confidence in you that he can admit if he has erred in anyway knowing that you still love him but will tell him the truth, & point out his errors & be there to help him & understand why he is behaving this way. He needs your love & honesty & your boundaries best wishes.

The main thing is to keep temptation out of his way, as Oopsminty says.
On the few occasions something like that has happened in our family, if you're fairly sure, I think it's best just to state that you know it was him. Don't give him an opportunity to lie by asking "Was it you?"
Sounds as if he's a chocoholic!

I think tell them. They are the parents so need the "bigger picture"

I agree. It's probably better to leave it.

He knows you know and that might well be enough to stop him doing anything like that again.

But don't be afraid to say something to him if you do catch him out again. Tell his parents if the behaviour escalates.

I agree.

I'd let it go. You are probably right that he ate it but I think it's best left well alone.

Stop the handbag game. Give them the chocolate when you arrive or hang on to your bag.

And cook the steak