Commenting on your question is a bit difficult unless the leave policy of your company is defined. As per the prevailing practice, most companies give CL for a maximum period of 3 days at a time. Sick leave without a medical certificate is granted for 3 days at a time, and with a medical certificate, the employee can avail whatever is credited to them. In certain genuine cases, advance SL of the next year is also provided. Similarly, for PL (earned leave), a minimum of three days is granted, and the maximum again depends on the company's policy.
In your case, the employee has already requested leave without pay, which you can approve if her boss has no objection. Leave without pay is an approved leave and falls well within the discipline of the organization. Absence is considered as indiscipline. In a nutshell, as per the Factories Act, an employee is eligible for one leave for every 20 days worked, and any additional leaves depend on the individual company's policy.
Regards,
Balakrishnan