What is the ruling on her praying the missed prayers in order, if she was overcome by sleep, and is what I did considered issuing a fatwa or offering advice, and when is it forbidden for me to advise her or remain silent about her?

It is not permissible to speak about religious matters without knowledge. Rather, one must verify what is advised. Regarding making up missed prayers, the fatwa we follow is that observing sequence between missed prayers is recommendable, not obligatory. Therefore, however the woman makes up her prayers, it will be sufficient for her.