Automatic distribution of working hours

Dear members, I have the following Excel table (see attachment).

I would like to note that my knowledge of both Excel and especially VBA is only amateur.

Now the complicated stuff. If I enter a number at J12, I would like to enter the hours automatically, irregularly and randomly between D13 to D43 with the start of working hours, E13 to E43 with the end of working hours and F13 to F43 break.

I've tried everything with formulas and VBA, I think it's impossible, but I've seen something similar before, so I really hope that one of you can help me.

Thanks in advance!!