Will the amount I forgave my paternal aunt, may Allah have mercy on her, be counted as an act of charity on behalf of my father, may Allah have mercy on him, knowing that I forgave her the debt after she had owed it to me, and I did not initially intend for it to be charity? And will I be rewarded for that?

Every act of devotion performed by a living person, and the reward of which is gifted to a deceased person, benefits the latter. So, if you absolve your uncle of a debt and dedicate the reward of this act of devotion to your father, your uncle will be relieved of the debt, and your father will benefit from its reward.

To ascertain whether you will be rewarded for this action, please refer to Fatwa no. 95640.