Is it permissible to use money designated for an Udhiyah - about which it was said: "This amount is for the Udhiyah, God willing" - to complete a daughter's marriage?

Regarding the money you collected, saying "This amount is for the Udhiyah, God willing" is a vow conditioned upon the will of God. This conditionality prevents the vow from becoming binding, according to the majority of scholars. It appears that you are not bound by anything from what was designated and conditioned upon the will of Allah the Almighty. Therefore, it is permissible for you to spend this amount on your daughter's marriage or any other permissible matters, especially if its benefit is great. Abd al-Razzaq narrated in Al-Musannaf from Bilal, who said: "That I give its price as charity - meaning the Udhiyah - to an orphan or a dust-covered person is more beloved to me than that I sacrifice it."