And the feminine affix cāp comes after the word āvaṭya,
The word अवट belongs to Gargadi class 4.1.105 which after taking यञ्, would have taken ङीप् (IV. I. 16). Thus आवट्या 'a female descendant of Avata'. But आवट्यायनी will be the proper form according to the Eastern Grammarians. See aphorism 4.1.17.,