Re: Nikah
It is clear now that if nikah is happening during periods and it is perfectly fine and valid then Ghusl is out of the picture. Ghusl is mentioned in my first post because girl and boy will recite some quranic ayat and it is recommended for the people to be Paak and with wudu when touching and reciting quran, Also I heard from molvis to have gusl before the nikah so I quoted you that, (I guess exception apply in the case of periods). I have also heard from the qualified Aalim asking during the ceremony if the girl is in this situation so he could take the next steps of Nikah according to that. I think he did the right thing I am not sure what he did after but I am guessing may be he explained to the boy and to the girl, the rights and the responsibilities during this situation.
If you search the google, you will find some links to this say you don’t need gusl and some say you can do gusl if you are not in that situation. So I guess you should ask the nearest Imam where you live, he may be able to give you much better answer.