Is it permissible to give charity, donate, or write a will for a baby girl born as a result of adultery with a married woman, knowing that "the child belongs to the [owner of the] bed, and the adulterer gets naught but stones," and what is the proper way to deal with this child?

The fornicator must repent to Allah for committing a great sin and abomination. He must also know that the girl conceived out of fornication is attributed to her mother's husband, and he has no relation to her. It is permissible for him, according to Islamic law, to give charity to her, or donate to her, or write a will in her name. However, it is better to conceal himself and her, and avoid anything that leads to scandal. He must distance himself from her. If she is in need, he may help her in a wise manner that does not make anyone aware of what occurred between them.