Perfume/cologne; twins; baby boost, none of that worked for me. Currently the families are in 11th to 13th generations. And just checked...one family still needs to win the lottery, while another needs to be cured of a serious illness. They love being gravely ill and cured, it seems:)
Try something:
Apply baby boost to both of them after the babymaking - make them start kissing while they are still waving after getting the baby boost.

That worked for me.
