diffent length of timeslots

Hi,

usualy we have 3 or 4 timeslots per day. And they have different length.

9-12 / 12-15 / 15-19 / 14-19

There is just one reservation for one of theese slots.
The problem is the time i have to set für timerange (how long a meal is estimated) max 180min and the dining block length with max 240min.

So in my case i define the slots and each slot is one possible reservation. How can i realize this?

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