Work schedule

Hi Experts,

We want to create a work schedule rule which should satisfy the following conditions.

1. work schdeule need to create with 3 days in a week, 7 hours working hours and 21 hrs for a week. Here the working days hasnot been confirmed.

2. This work schedule is applicable only for contract employees.

3. What would happen if I need to hire a new contract employee who will work 7 hours per day and 4 days per week which is 28 hours per week? I won't be able to use the work schedule with 21 hrs. Kindly guide me how to change/configure work schedule for this scenario?

Regards

Vani