Bedtime woes DCs 7 & 10

[shebird]

Bedtime for my DCs seems to have gone to pot. Having once been the very proud and smug mum to two excellent sleepers I am now at my wits end with the bed time capers in this house.
DD2 goes to bed at about 730, has a story and then instead of falling to sleep spends the next hour playing about or coming downstairs. DD1 goes to bed at 830 and then follows an hour of chaos as the both muck about running into each other's rooms. I have tried earlier/ later times, rewards, punishment with no success and now at my wits end. Has anyone any bright ideas to help solve this problem?
Thanks

Are they getting enough daylight and exercise? Have you tried booting them off the tablets/mobiles etc for an hour before bed?

What's your wind down time like? My DS is nearly 10 and goes upstairs at 7.30 and we do stories till about 8. Not many parents seem to still be reading to them at this age but my DS seems to settle better. Dd is 6 and its light out at 7pm. She has a story before this.

In the holidays we let it slip.

TBH it is DD2 that is the problem she seems to struggle to get off to sleep despite story time for about 20 minutes. Because she is still awake at 830 when DD1 goes upstairs then the trouble starts with her going into her sisters room.
They walk to school, do sport, swim and dance so I think they are pretty active. I think the no tablet idea might be worth looking into though so thanks for that.

Do you think starting dd2s bedtime routine a little earlier might help?

My bf had difficulty in getting to sleep recently. They told her to get up at a set time, say 8am. Not to use electronics after 5pm and to go out for a walk after her evening meal, have a bath, a milky drink and read. They also advised doing sport. So basically a really, really long wind down.

All of these seemed to help and she's back on track now