Is it permissible to perform the 'aqiqah from money designated for charity (sadaqah), and would it be counted as part of the fixed percentage allocated for charity?

If the donor intended charity without uttering a vow, then nothing is binding upon him, and he is permitted to perform the ‘aqīqah with money. However, if he uttered a formula of covenant with Allah, it could be either an oath and a vow, or an oath only. If he committed to it as an act of drawing closer to Allah (qurbah), then it is both a vow and an oath. In this case, he is not permitted to spend the vowed amount on the ‘aqīqah, nor is he allowed to eat from it.