Paving and neutralizing a trip hazard - Ideas

Hello everyone,

I am racking my brain about the options I have. Maybe you come up with ideas I have overlooked so far. Here is my plan and some information about it.

1. The red hatched terrace area should be paved uniformly (Weserwaben natural stone look concrete slabs 3cm thick) - so both the already existing area and the lawn area
2. Edging with matching curbstones
3. Raising the entire paved area by about 10 cm to eliminate the trip hazard after two beers at the terrace door
4. The slabs are currently fixed with concrete wedges
5. The slabs lie on gravel, have a slope and have been stable there for 15 years.
6. On the house wall side there is a bitumen waterproofing up to the top edge of the gravel, no studded membrane

My preference would be:
1. Set curbstones
2. Keep the existing paving, put gravel on it (5cm), level and put new slabs on top
3. Proceed on the lawn area with the usual method (excavation, compaction, gravel, leveling, paving)

Otherwise:
1. Remove slabs
2. Remove gravel
3. Raise compacted area
4. Replace gravel, level, pave

My questions:
What do you think of the possibility to pave over the existing paving?
If I excavate the lawn area and remove the concrete wedges, will the subsoil of the existing paved area flow into the excavated area?

Thanks for reading!
Patrick

Regarding 3) What about rain? If you raise your terrace, the water might press against the terrace door during heavy rain. I would have installed a channel in front of the door as well, but then you definitely have to remove all the slabs and start the big program. Otherwise, it is definitely possible. The gravel will probably scatter a bit, but if no one stomps on the edge, it is not a problem.

Thank you for your answer! The whole thing has a slope, but a gutter would still probably be useful. As far as I have researched now, it will probably be the large size.