Invalidation of the Sukkah on Shemini Atzeret When the Host is from the Diaspora

To the esteemed Gaon, Rabbi Amram Fried, shlita, greetings and blessings. I am an avrech residing in Jerusalem, and during the recent Sukkot holiday, a practical question arose for me, for which I sought the Torah opinion of your honor. My father-in-law, who lives in France, came to Israel to celebrate Sukkot with us. When Shemini Atzeret arrived, during which Jews from the diaspora customarily eat in the sukkah, I saw in Yabia Omer (Part 9, Siman 62) that it is written that someone who comes from abroad and has Israeli guests does not need to eat in the sukkah (especially since it was very cold at night, and the sukkah was not pleasant for us, and the words of Korban Netanel, mentioned in Yabia Omer there, can be added). However, a local rabbi suggested a "solution" to my father-in-law to invalidate the covering over the part of the sukkah belonging to the Israeli, so he could sit with him in the same sukkah without concern. My father-in-law, in his simplicity, placed a wooden partition (about 50 cm wide) on my part of the sukkah to invalidate the covering over me. I pointed out to him that it is not clear at all if such an action is effective, as the Gemara in Sukkah (48b) explains that a disqualification of 4 tefachim is required, and Tosafot there question what the law is if it is less than 3, and the early commentators (Raavad, Ramban, and Meiri) wrote that a significant distinction is required, etc., besides the fact that the aforementioned partition is kosher by Torah law and invalid only due to a decree. The question is, therefore: Is there indeed room for this leniency — to invalidate part of the sukkah for the purpose of a diaspora Jew sitting in it, when the rest of the covering is kosher? And if so, is it sufficient to place the aforementioned wooden partition, or is a complete disqualification of 4 tefachim or a clear distinction visible to all required? Does it matter that the sukkah itself belongs to my father-in-law (a diaspora Jew), and I am only a guest in it, regarding the need to invalidate or eat at home? Thank you in advance for your honor's attention and clear guidance. With the blessing of the Torah, Yosef Shalom Tuito, Jerusalem.

Greetings and blessings 

Response of our teacher, the Gaon, Rabbi Amram Fried, shlita:

A distinction is sufficient even if it does not truly invalidate the sukkah, as explained in Sukkah 48 and in Siman 606

Even according to the main law, one is exempt from the sukkah, as explained in the attached note