How to recite the Mu`awwidhatayn for children
Question

Is it permissible to blow into my cupped hands and recite the Mu`awwidhatayn [the last two surahs of the Quran, seeking refuge with Allah] and Al-Ikhlas, then wipe the hands over all the children in one go, or must I recite them three times for each child separately?
Praise be to Allah.It is permissible for a person to recite the Mu`awwidhatayn, blow into his cupped hands and wipe his child with his hands.
It was narrated that Abu Sa`id Al-Khudri (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) used to seek refuge from the jinn and from the evil eye until the Mu`awwidhatayn were revealed, after which he began to recite them and stopped reciting other prayers. (Narrated by At-Tirmidhi (2058); Al-Albani classed it as authentic in Sahih At-Tirmidhi)
Blowing with some saliva [into one’s cupped hands] and reciting the Mu`awwidhatayn is based on the practice of the Prophet (blessings and peace of Allah be upon him) just before going to sleep. He used to recite [the Mu`awwidhatayn] into his cupped hands and blow into them, then he would wipe his blessed body with them. When he fell sick, ‘Aa’ishah would do that for him, which indicates that for a child, his mother can recite the Mu`awwidhatayn and blow into her cupped hands, then wipe the child with them.
It was narrated that `Aa’ishah (may Allah be pleased with her) said: When the Messenger of Allah (blessings and peace of Allah be upon him) went to his bed, he would blow into his cupped hands and recite Qul Huwa Allahu Ahad [Al-Ikhlas] and the Mu`awwidhatayn, then he would wipe his face and whatever of his body his hands could reach. ‘Aa’ishah said: When he fell sick, he would tell me to do that for him. (Narrated by Al-Bukhari, 5748).
Dr. Ahmad Al-Qadi (may Allah have mercy on him) said: I asked our shaykh [Ibn ‘Uthaymin] (may Allah have mercy on him): How may we recite wird [daily litany] over children?
He replied: You should put your cupped hands together, recite and blow into them, and wipe them over the child. But if the child is not with you, then it will be a supplication (Du`a’), not recitation. (End quote from Thamarat At-Tadwin, p. 9)
If someone wants to seek refuge with Allah for more than one child, is it sufficient for him to wipe his hands over both children in one go, or should he do that for each one separately? We have not come across anything regarding that, so to be on the safe side, he should recite ruqyah and wipe his hands over each child separately.
For more details, please see the answer to question no. 174933 .
And Allah knows best.