In an earlier post I said,

"For the remaining such oaths taken by bride and bridegroom during the
marriage ritual, you might want to refer to one of the huge number of
publications of Vivaha mantras abundantly available on and offline"

For the specific instance enquired by Prof. Rajam,

let me direct you website addressing Tamil audience:

Placing a Child on B's Lap:
So far, B has been sitting to the right of BG. Now she shifts and sits to his left side. A male child from a family in which no death of a child has taken place, is made to sit on the lap of B. ( The idea is B should get such healthy male children.) The child is given fruits with a mantras which convey the following meaning:
"Oh fruits, as you cause growth in those who eat you, bless this girl with good progeny."
"Let the children so born bring love and affection."
Addressing B, the mantra says:
"Be aware of your duties to your husband and guests; propagate good deeds to all those you have contacts."
"Let this pure girl be blessed with happiness and prosperity."

Prof.Nagaraj Paturi

Hyderabad-500044