Use of existing pavement base

Hello,
the time has come - the old exposed aggregate concrete slabs at the entrance gate through the front garden are to be replaced by a mix of various concrete pavers/slabs. For this purpose, we are collecting various formats (also a few natural stones and bricks will be mixed in) and will lay them in a random pattern (otherwise it doesn’t really work).
Now to my question: under the exposed aggregate concrete slabs there is an about 25 cm high sand layer (grain size up to max. 2 mm - I suspect building sand). Whether the layer underneath was compacted I can hardly say ... in any case it is not gravel but rather appears like a collection of topsoil, stone and brick debris. The whole thing is quite firm (whether it was actually compacted or if the years have simply left their marks, I cannot say). Do you think I could simply lay our stone mix in place of the exposed aggregate concrete slabs without the stones sinking within a short time?
Thanks very much for your advice.
Best regards, Chrisu

Hello, what kind of house do you have? An older one? Recently bought? How long have you lived with concrete slabs? Tell me.

The whole thing is quite solid (whether it was actually compacted or if the years have simply left their marks, I cannot say.)

If the slabs have been lying there for 30 years, it will probably be solid and compacted; if you only laid these slabs there temporarily last year, maybe not.

And then it also depends on what your goal is. Do you want it to be somewhat natural or completely smooth and even? The latter, I believe, less so, since you probably want to apply some patchwork? Do you have different heights as with paving stones?

Hello, the house is about 70 years old and I suspect that the exposed aggregate concrete slabs have been around for several years, possibly decades. Attached I have laid out one square meter for you ... this is roughly how I imagine the path ... basically, I assumed a level installation, although I believe that the "naturalness" will come automatically, since I am handy but have never laid paving before ;-).

Have you also already considered how you want to compensate for the extreme height differences?

Quite naively thought: with a lot of patience, the stones are set in the sand deeper or less deep depending on the size ...

Then give it a try - you'll never get it clean that way.