False accussations from a minor

Good day! I am speaking in behalf of a friend who is in need of council. He was accussed by a 16 year old girl of impregnating her and that they had a relationship. Here is what happened. The man accussed knows the girl through drinking sessions since late May and early June. The girl all the while was seeing a lot of men, and she even calls the accused "kuya" (big brother). Then the girl moved from the province to NCR to work as a maid in a family her mother arranged for her. While being there, she had her menstruation around mid-July and then she started calling my friend, saying that he is the father and that she had told her mother. Her mother spread the news and went to the house of my friend, threatening that of he won't give her a capital for a small business and if he won't take in her dau, she would file a case to DSWD. My friend tried to explain, but with the threat of imprissonment and his name defamed, he was left with no choice but to agree. So they went to the barangay and had a contract signed with a video recorded saying, he is to get them (the pregnant girl and her family) into a boarding house and he has to give Php5,000 to the mother and give a monthly allowance until the child comes out. And if both parties chose for them tp be wed when the right time comes then it will be so, but my friend just wants to get it over with so he will work and give the said money allowance. Everything was as it was agreed on, he got them a boarding house and finding a way to pay the Php5,000 as well as looking for work to be able to give the monthly allowance for he is jobless before this. But, now the girl is gettimg restless for she is threatening to move forwad with the case, because she wants my friend to be intimate with her. My friend does not even want to see the girl for the trouble she has caused him. She is just waiting for her to reach 18.
They also went to the doctor already, she was ask when was the last time they had sexual intercourse (if they had). She said, June 6. And when dis she had her period. She said July 15. The doctor tried to explain that my friend can't be the father of the child since she had her period even after they last saw each other, but she kept on denying.
With that her credibility is already tarnished, right?
What should my friend do?
Her mother even allowed her to live in with another man when she was 15 years old but the man was somewhat "poverish" so that could be a reason why they did not file a case. She is also known to have intimate connections with a lot of men with money involved.
Does he have good grounds to file libel or defamation?

Yes! And use the doctor's statement as one of the evidence if he is sure that she had menstration the time he left her. File a counter affidavit stating all of these and if lucky enough they will back off if they know he is willing to fight back. Hanapin mo na rin ang mga dating lalaki nya para may mag testify na kung anong uri syang babae dahil kapag wala kang ibang witness na ganito pasok sya Staturoty rape dahil 15 lang sya. Kailangan mo ng mahusay na abogado dito.

Thank you po. Yung situation po nila right now is, nag usap na po sila sa brgy. na yung girl po is tutustusan nung friend ko yung girl until manganak yon, in the agreement, implied na po na may relasyon sila kahit wala po and tumira na po nang ilang days yung girl sa tinitirahan niya (which is sa uncle niya), so sabi daw po pwede daw po seduvtion ikaso sakanya in case po tumagilid yung girl kasi po paiba iba isip, gusto pa po pakasalan siya (since hindi po pinapansin nung friend ko kasi po syempre galit siya don, gusto pa po nung girl lambingin siya porket siya daw po yung agrabyado dahil buntis siya). Yung kasulatan po sa brgy. pwede po kaya malaban sa sasabihin ng friend ko? kasi po wala talaga sila relasyon but since inipit na siya, wala na siya nagawa kundi pumirma doon, lalo na po ang proseso sa DSWD is kahit wala naman po katibayan yung babae, basta mag file ng case lang, makukulong na yung lalaki habang pino-proseso yung kaso. Yun lang po iningatan niya dahil gusto din niya maka pag trabaho na walang record (wala pa po siya bad record sa nbi e).

Pagkapanganak ipa DNA nya ang bata at kapag hindi sa kanya pwede nyang kasuhan ito!