The Agnihotra is an essential Vedic ritual that a householder must practice. In practise we see both husband and wife sitting together to do it. For example here.
Further the dharmashastras prescribe that in case the husband is away, the wife must tend to the fire alone. We have statements from among the ashtadasha Smritis where women do perform agnihotra. (I think Atri smriti has it faintly recollecting). However off late there was a statement talking about the prescription of the Manusmriti.
Currently, the Manusmriti says:
For females the Rites of marriage have been ordained to be their ‘Vedic Sacrament,’ the serving of the husbands their ‘residence with the Teacher,’ and the household-duties their ‘tending of fire.’—(Manu 2.67.
The site said that commentator Kulluka Bhatta notes that some manuscripts contained the following verse:
अग्निहोत्रस्य शुश्रूषा सायमुद च। कार्या पत्न्या प्रतिदिनमिति कर्म च वैदिकम्॥
Attending to the Agnihotra daily and assisting her husband in his duties at dawn and in the evening everyday in the performance of ceremonies are the Vaidika Karma of women.
The site further went on to give reasons as to why this verse seems to be the true verse:
I am sure this was the original verse and the former two (which contradict this one) are interpolations, because the Ramayana clearly record that Kaushalya Rani, Devi Sita etc. used to attend to the performance of Agnihotra everyday, and the Atharvaveda too prescribes that the primary responsibility of performance of daily household rituals lies with the wife.
I would further like to add that this statement is in accordance with that described in some other Smritis (as mentioned above) as well as the practise followed by the few remaining Agnihotri Brahmins. I have checked the Kulluka Bhatta commentary here but not been able to locate this statement.
Question
Would like to know where the above reference allowing women to perform agnihotras is found in the Manusmriti (old manuscripts) and mentioned by which commentator.