Query Regarding Switching to New Syllabus for CS Executive and Exam Validity

I qualified for the CSEET in 2020, and my registration is valid until November 2025. Currently, I am attempting the CS Executive exams under the 2017 syllabus, but I don't feel hopeful about it. I am considering switching to the new syllabus and applying for only one group in the June 2025 exams. Could you please let me know when I can apply for June (only for one group, after switching to the new syllabus), given that I am already enrolled for the exam? Additionally, if I pass Group 1 in June 2025, can I attempt Group 2 in December 2025, considering that my registration is valid only until November 2025?