How should one supplicate for the deceased in the funeral prayer if the person was male, female, or two individuals, and how should one supplicate if the deceased was a child?

One supplicates for all the deceased by saying: "O Allah, forgive them and have mercy on them..." And for two, "O Allah, forgive them both and have mercy on them both..." As for a child, the supplication for him is: "O Allah, make him a treasure for his parents, and a forerunner and an answered intercessor. O Allah, magnify their rewards through him, and make their scales heavy with him, and join him with the righteous predecessors among the believers, and place him under the care of Ibrahim (peace be upon him), and protect him by Your mercy from the torment of Hellfire."