However my question still remains how can a child be called the progeny of the father alone ? what about the mother aren't her children her progeny too? like we say that if Bibi Fatima S.A. wasn't there Imamat wouldn't be there like wise i am asking it is through Bibi Narjis S.A that we have our Last Imam A.S. so shouldn't the children be the progeny of both parents? please guide me if I'm wrong.

Walaikumussalam
Generally children they are attributed to father but it is truth that children are progeny of both and nice example you have mentioned.
In ziyarate Warisa we recite
اَلسَّلاَمُ عَلَيْكَ يَا بْنَ عَلِيٍّ ٱلْمُرْتَضَىٰ

alssal¡mu `alayka yabna `aliyyin almurta¤¡

Peace be upon you, O son of `Al¢ the well-pleased.

اَلسَّلاَمُ عَلَيْكَ يَا بْنَ فَاطِمَةَ ٱلزَّهْرَاءِ

alssal¡mu `alayka yabna f¡§imata alzzahr¡'i

Peace be upon you, O son of F¡§imah the luminous lady.

اَلسَّلاَمُ عَلَيْكَ يَا بْنَ خَدِيـجَةَ ٱلْكُبْرَىٰ

alssal¡mu `alayka yabna khad¢jata alkubr¡a
At another place it comes again

اَشهَدُ اَنّك كُنتَ نوُرا في الأصلابِ الشّامِخَةِ وَالأرحـامِ المُطَهَرَةِ
I bear witness that verily you were a light in the sublime loins and purified wombs

لم تـُنَجـِسـكَ الجـاهِليَّةُ بـاَنِجـاسـِها
The impurities of ignorance did not even tough you
Wassalam