forget the friend... if she goes n tells mil that the kid i claimed is mine, is not mine but infact u'r sister's.. would he believe her? even if she had told it in the beginning itself, mil wouldn't have believed her.. Because everything said and done, sukruti is his sister, the same sister he brought up.. He would never believe prachi, over such a sensitive issue over sister... more over it wasn't her place what so ever to go telling milind the truth... somethings are better left alone, till the right person and right time... it should have been sukruti who told milind the truth... no matter what prachi said or did, the baby is her responsibility.. she shouldn't have let prachi brainwash her into not telling her own brother n father...
I think he would have definitely believed that Suki was the mother had she told him on Ritwik's birthday. In fact at that point of time even if she had told him what she told him today, that while she is not the mother, she is covering up for someone close to them, he would have believed because he had implicit faith in Prachi. In fact he agreed to SS marriage only because it would make Prachi happy. He trusted her judgement. Later when Suki came back she should have encouraged her to tell the truth to her brother before he gets to know through other sources. Afterall she is her bhabhi and has a moral responsibility to her when she knows Suki is not doing something right.
On the other hand she is brainwashing her not to tell her own brother. Suki did not allow herself to be brainwashed because she did tell her brother. Only he was sleeping. Later she asked Prachi to tell him everything. It is Prachi's fault that she did not. Even now Suki is under the impression Prachi had told the entire truth and Milsi still does not believe it.
And the fact is Milsi knows about Suki-Alaap affair. So it is not difficult for him to believe that Suki is the mother. Only Prachi never gave Milsi the chance to decide for himself.