Fiber optic connection is being installed - use existing multi-utility infrastructure?

Could it be that this might possibly be rejected for liability reasons? Especially if the cable (or the orange tube for DG) is to be installed afterwards and deviates from the company’s standard procedure? The order situation also allows for orders to be rejected (at other times, orders can of course also be rejected ...)

Rule number one:
"Whoever went last is to blame"
Rule number two:
---

It's up to you to tell them where to go. At best, you dig out the multi-utility connection for them in advance.

No. If the customer demands something that violates DIN, VDE, TAB, or anything else, or puts the executing contractor/employee liable for all consequences... see rule number one... then they will not do it. Even if it is based only on experience or the entrepreneur’s principle.
My electrician didn’t want to install a socket by the window next to the toilet because you can reach the bathtub with a typical Christmas light... according to DIN, VDE, etc., such a socket would have been perfectly fine, all distances observed... but he doesn’t do it because he knows of cases where children took the lighting into the bathtub... Boom.

Rule number one: "Whoever was last is to blame" Rule number two: --- No. If the customer demands something that violates DIN, VDE, TAB or anything else or puts the executing contractor/employee liable for all consequences... see rule number one... then he will not do it. Even if it is only based on experience or the principle of the contractor. My electrician didn’t want to install a socket at the window next to the toilet because you can reach the bathtub with a usual Christmas light... according to DIN, VDE, etc., such a socket would have been completely fine, all distances observed... but he doesn’t do it because he knows cases where children took the light into the bathtub... bang.

DIN is only a recommendation. Whether there is a regulation opposing it in the context of multi-utility installation, we have not yet clarified. Sad that one is so dependent on craftsmen. It should actually be the other way around; I as the customer should decide what is done. I also take responsibility, as long as it is within the legal framework. Normally one would say, then I just take a craftsman who does it the way I want, but that does not work at the moment.

If you as a customer take full responsibility for any damages, every craftsman will gladly throw the stuff into the multi-utility area. But if you don’t, the "I’m an amateur, HE is the expert" card will come into play at the latest in court... And that brings us to DIN as a recommendation. That only applies as long as you can prove that your solution meets DIN or better. Have fun if you just shove a cable into a DIN feed-through that is already occupied. No expert on this planet will judge that as "DIN or better."

If you as a customer take full responsibility for any damages, every craftsman will gladly throw the stuff into the multi-duct for you. But you don't do that; at the latest in court, the "I am a layman, HE is the expert" card comes into play... And that brings us to DIN as a recommendation. That only applies as long as you can prove that your solution meets DIN or better. Have fun if you simply shove a cable into a DIN conduit that is already occupied. No expert on this planet will judge that as "DIN or better."

This was about a free conduit, not an occupied one.

This was about a free execution, not a fitted one.

Same.
The installation must be sealed properly, otherwise all damages/consequential damages are the responsibility of the craftsman who worked on it last.
Because even in court, contrary to before, the rule is:
Rule one:
Whoever worked on it last is to blame
Rule two
Whoever worked on it last and does not want to be blamed must prove it beyond doubt (with expensive expert reports)...