Adding additional holidays for a Flexible contract

I have someone who is on a flexible contract so their holiday obviously accrues based on average days / hours worked. However she is on maternity at the moment so accruing neither and her holiday allowance is currently showing as zero

I have 14 days holiday outstanding from last year that I need to add onto her allowance – if I change her record to HOLIDAY NOT CALCULATED then I can add these but she potentially won’t then accrue any holiday when back at work? Is there another way for me to add these holidays onto her allowance without it messing up her correct accrual?