Here are some sources I found online regarding the Mishna Berurah relying on Kisvei Yados (I know people call it “Kisvei Yad,” but in Mishnaic Hebrew I think we make both words plural, like Batei Kneisios and Batei Medrashos):
??? ????? ???? ???? ??: “???? ??? ?????? ???? ?? ???? ???? ????? ????? ?????? ????? ??????”; ????? ???? ???? ?? ?”? ??????: “????? ??? ???? ??? ????? ????? ?????”; ???? ????? ???? ?? ?”? ?: “?? ????? ??”? ??? ????? ????? ?????”; ????? ???? ???? ???? ?”? ?????: “??? ????? ?????? ????? ?? ??”? ????? ????? ???? ???? ??????”.
???? ????? ???? ??? ?”? ?: “??? ??”? ??????? ?? ????? [?????? ??? ?????] ??? ?”? ??? ????? ??”; ????? ???? ???? ??? ?”? ??????: “??”? [?????? ????? ?????]”; ????? ???? ???? ???? ?”? ????: “???? ??? ????? ????? ?? ????? ?????”; ????? ???? ???? ???? ?”? ????: “???? ?? ?????? ??? ????? ?? ????? ????? ???? ????”; ??? ????? ???? ??? ?”? ?: “?? ????? ????? ?????? ??? ????? ???? ?????”.
????? ???? ???? ?? ?”? ???: “????? ???? ?????? ?????? ??? ?????”.
Regarding the “klal” that we assume an Achron would have changed his mind had he known of the Rishon, see the Maharik quoted in the Hebrew Wikipedia site: Hilchasa Kibasrai.