To worry about DC going on holiday with GP

[CoffeeDeprivation]

Just that, really. We get along well, they love the kids (6&4) but they have never looked after them on their own. Occasionally, they have done babysitting (once or twice a year) in my house. They have taken them to the park a handful of times on their own. They suggested this year that they could take them on a holiday in summer (a week) down to the beach. On the one hand, it sounds great, we rarely have time as a couple and never had a full day together without kids, so it would do us good. The kids love their GP and would love to go. But part of me is worried that GP have underestimated how tiring it is (they are healthy but have the occasional blip due to old age), that they won't be able to keep an eye on both and the youngest might run off into danger (you have to keep all eyes on this one), that after two days they will have more than enough and will resent offering or would just not have the energy to look after them, etc.

The kids have never slept anywhere else either, I don't think they will miss us but have very different bedtime conditions (ceiling light / dark room, music/silence, reading/straight into bed) and I am not sure how they will deal sleeping together in the same room.

I don't know, I'm worried that they will injure themselves or put themselves in danger, either because GP don't reach them on time or because tiredness takes its toll.
I also know that this might be a tricky issue for me because this fear happened in my family, when my GM could not reach my cousin when he run into the road. They had gone out for the day and neither were familiar with the surroundings. I was a toddler myself when it happened (so I didn't experience the trauma directly) but the story has followed me since. No one took anyone on holidays on my family. Days out when older and rarely.

So am I afraid because of my childhood story or is it reasonable to think these are not optimal conditions to take kids on a holiday?

JasperKarat someone always scathingly points out that grandparents have raised their own children, but if a prospective employee hadn't done a job nor had any experience of the industry for 30+ year, and the way things are done and relevant external conditions had changed a lot, no employer would give them a senior role and throw them straight into it with no handover or extensive refresher training.

So many grandparents who don't have ongoing childcare experience don't fit car seats properly or think it's fine not to use one for a short journey, ignore or misunderstand allergies, ignore safe sleeping advice in babies, leave young children unsupervised near water and dogs, smoke around children, and live by the mantra "you survived" more by luck than judgement

Even with the best will in the world it's very rarely sensible to volunteer to do something 24/7 for 7 days when your last experience of doing that thing was 30 years ago. Memories are selective and things that you don't remember as tiring at 35 may very well be at 65...

If they don't have and dont want experience of looking after the children together for at least a 48 hour period (so carrying on through another 24 hours after having them a day and a night, to get an idea of whether or not it's tiring) then I'd veto a week away with a 6 and 4 year old, absolutely.

someone always scathingly points out that grandparents have raised their own children

Exactly. DH's dad used to let him and his cousins ride on the back of a pickup truck when they were kids. His mum used to go to the shop and leave him locked in the house when he was about six, I think.