Who is responsible for the financial support of minor children after the death of their impoverished father? What should the guardian do with the orphans' money, and does the guardian guarantee the money when investing it?

After the death of their father, the maintenance of poor children becomes obligatory upon every relative who inherits from them, whether by fard (fixed share) or ta'sib (residuary), provided that relative has more than enough for their own personal expenses. If there is more than one such relative, the maintenance is divided among them in proportion to their share of inheritance from the children, as mentioned by Ibn Qudamah. However, if the children possess wealth, the guardian is to spend on them from their own money. The guardian must manage their wealth in a way that is in their best interest, by preserving the principal assets, developing the offshoots, spending on them in a reasonable manner, and fulfilling the rights related to the wealth, such as Zakat.