Randomly assigning employees to different groups

So im having trouble assigning employees to different departments at my work.

Say theres 12 employees and 4 different departments (A,B,C,D).

Some days 3 people are working in each department. Randomly assigning that would be easy. However, most days, department A only needs 2 people or department D needs 4. Some days one department wont be running at all.

Ive been messing with Rand() roundbetween rank, but i cant seem to figure out how to do this with differing group sizes. Is there a way i can input how many people i need in each department and have it randomize the right number of employees for each department based on my necessity??

Even a nudge in the right direction would be great. Im ignorant. Thanks in advance!

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Here are two examples :

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Awesome. Exactly what i was talking about. Thank you!

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You are welcome.