The discussion about Pilegesh is in Shulchan Aruch in the very beginning of Laws of Kiddushin chapter 26:1. There we find that if a Pilegesh fears to go to the Mikva it is a terrible problem. But if she goes to the Mikva the first shita in the Ramo is that a Pilegesh is permitted, of course, if she goes to the Mikva. The Vilna Gaon there says that the opinion that Pilegesh is permitted is an open gemora in Sanhedrain 21A, that Pilegesh is without Kiddushin. Meaning that Pilegesh is a real form of marriage. The Ramban says clearly in Mehuchesses of the Rashbo which contains certain teachings clearly labelled as not the Rashbo but the Ramban, we find the Ramban very strongly backing Pilegesh, and he says that the Rambam himself, if the couple marries a real marriage which is not Zenuce, approves of Pilegesh. I feel that with all of the rabbis who don't know hilchose Gittin and are encouraging women to remarry with invalid Gittin or no Gittin, and these women will make mamzerim, and it gets worse all of the time, it is better to do Pilegesh which is permitted by an open gemora than to do Kiddushin and make mamzerim. The Yaavets also strongly backs Pilegesh. But nobody backs mamzerim.
Thus somebody who curses me for choosing Pilegesh over mamzerim, and then he laughs at the curse when I call him up, has a very interesting way of showing how a head of a Gittin Beth Din is supposed to behave.
I DO NOT FORGIVE HIS CURSE AND I DON'T FORGIVE HIS LAUGHING AT ME WHEN I ASKED HIM ABOUT IT.
LET HIM EXPLAIN WHY HE IGNORES THE MODERN VIOLATION OF HALOCHO WHERE MANY WOMEN ARE TAUGHT BY RABBIS TO FORCE THE HUSBAND TO GIVE A GET EITHER BY GOING TO SECULAR COURT OR OTHER WAYS OF FORCING OR AS SOME DO THEY JUST LEAVE THE HUSBAND WITHOUT A GET. DOES HE BELIEVE THAT THESE WOMEN WILL HAVE MAMZERIM? DOES HE BELIEVE THAT FORCING A GET IS A MINOR SIN? LET HIM LOOK IN EVEN HOEZER KESUBOSE 77:2 IN THE GRO #5 WHO SAYS THAT EVERYONE AGREES THAT A GET MAY NOT BE FORCED AND HE REFERS TO TOSFOSE KESUBOSE 63b IN RABBEINU TAM WHO SAYS THAT THERE IS A CLEAR GEMORA IN NEDORIM 90B THAT IN EARLIER GENERATIONS WOMEN WHO SAID CERTAIN THINGS MERITED THAT BETH DIN FORCED THE GET BUT IN LATTER GENERATIONS THIS STOPPED BECAUSE WE ARE AFRAID THAT SHE JUST WANTS TO MARRY ANOTHER MAN SO SHE SAYS LIES ABOUT HER HUSBAND TO FORCE HIM TO GIVE A GET. IF SO THIS IS A LAW FROM THE MISHNEH THAT TODAY NO WOMAN CAN BE GIVEN THE POWER TO FORCE HER HUSBAND TO DIVORCE HER. ON THE SAME PAGE WITH THE GRO IN KESUBOSE 77 THE SHULCHAN ARUCH AND THE RAMO AND THE BEIS SHMUEL AND THE CHELKAS MECHOKAKE ALL AGREE, AND THEY QUOTE A RASHBO VII: 414 THAT THE HUSBAND MAY NOT BE PRESSURED TO GIVE HIS WIFE A GET.