sabbastical leave & annual leave

I would like your advice on how to pro rate A.L taking into account that the said employee will be taking an unpaid sabbatical leave. She joined this year in March. And currently (i.e without the sabbatical leave) after prorating she has 11 days of AL and has claimed 4.5 days so far.

And she is entitled to 14 days AL.
Sabbatical leave is a mutual agreement between employee and employer, in which employee is granted extended leave. It could range from a couple of months to as long as a year, either paid or unpaid - and is outside of employee’s normal annual leave entitlements.
Hence, you may prorate her annual leave as below:
(No. of months in service/12) * Annual Leave Entitlement
(No. of calendar days served)/(No. of calendar days)*Annual Leave Entitlement