shalom,
regarding the mishnah I was interested to learn whether a giyoret could be in yichud with or marry her father,brother etc.please furnish sources.
The Gemara in Yevamos 22a writes that mid'Oraisa a Ger is permitted to all of his relatives, but mid'Rabanan he is not permitted to marry them, so that he should not say that he came to a lesser Kedushah through conversion (and is permitted to relative to which he had previously been prohibited).
As for Yichud,the Heter to be Meyached with a father or mother does not stem from the Isur but rather from the natural aversion to incest. Therefore, Igros Moshe (EH 4:64) allows Yichud with a father. However he is discussing a situation where the father had also converted; where he is non-Jewish it is likely that it is Asur.
Dov Zupnik
Of course there is difference between Sh'air Ha'eim, and Sh'air Ha'av, YD 269, and see MaHARShA Yuma 28b that that is why Yaakov was allowed to marry two sisters.
>> As for Yichud,the Heter to be Meyached with a father or mother does not stem from the Isur but rather from the natural aversion to incest....<<
See also Ramban on Unchayeh Movinu Zora (Breishis 19:32)