Pregnancy and effectiveness of postinor 2

Hello Doctor. If a girl was having intercourse 3-4 days before ovulation, and consume Postinor-2 right after the coitus, it is said P-2 would delay her ovulation. Which could prevent her from pregnancy. And then the girl has another coitus on the supposed ovulation day (which may be delayed due to previous P-2 consumption), and also consume the P-2 after the coitus, will that second intake of P-2 working? Somehow the boy who is the partner said that he took an extra precautions like ejaculated outside of the girl, washed his genital before having another coitus on the same session, and sometimes wearing condoms during different coitus on same sex session. Like one night, they having 2-3 coitus where at firstthe boy didn’t wore any condoms but ejaculated outside of the girl vag, then he washed his genitals again before having second coitus, and then washed it again and wearing condom for third coitus. So can pregancy be prevented ? Thank you doc.