What should a man do with a CD belonging to his first wife, which he found in his office, knowing that his current wife might be upset if she saw the disc, and returning it to the first wife could cause problems, especially since the first wife is getting married soon?

If this CD belongs to your first wife, it must be returned to her, unless you fear a greater harm, in which case you should donate its value on her behalf. Scholars have stated that if a minor item is difficult to return to its owner, its value should be donated on their behalf. They mentioned that one has the choice between handing it over to the ruler or donating its value on behalf of its owner. Therefore, you may give this CD to someone who will benefit from it, and the reward for that will go to its owner.