Is it possible to lay terrace slabs on split over an old foundation?

Hello, as the title already says, I want to lay new terrace slabs on grit. The old slabs are 5 cm thick and were glued to the foundation. The new slabs are 2 cm thick. I want to lay them on grit because I also want to widen the terrace. For that, I would of course have to work with crushed stone + grit. Is that possible without any concerns, or what would be the best approach?

Sure, it works, just compact properly

If there is a slope, use a drainage mat as a base, then 3-5 cm of gravel. Otherwise, create a slope with screed. Important: do not omit the drainage mat. Compact carefully when connecting to the widening.

Drainage mat only important at the part with the foundation, or completely?

*edit* Slope is present

Only at the foundation. The applied widening with frost protection gravel about 40-50cm thick. Water the gravel a little before compacting, tamp it down, and tamp it again the next day, then there will be no settling even after 10 years or later.

Thank you :-)

Then I will slowly start taking care of everything.