This is a portion of dialogue between Brahma and Narayan, given the second sarga of Adhyatma Ramayan.
मानुषेण मृतिस्तस्य मया कल्याण कल्पिता ॥
अतस्त्वं मानुषो भूत्वा जहि देवरिपुं प्रभो ॥२४॥
श्रीभगवानुवाच ॥
कश्यपस्य वरो दत्तस्तपसा तोषितेन मे ॥२५॥
याचितः
पुत्रभावाय तथेत्यङ्गीकृतं मया ॥
Here कश्यपाय in the place of कश्यपस्य would have been a regular format to convey the meaning.
I may have read such constructions, but do not remember any.
Best regards,