E2
=SUM(IFERROR(1/MMULT(COUNTIFS(A$2:A$18,REPLACE(INDEX(TRIM(MID(SUBSTITUTE(TEXT(B$2:B$18,"[="&C2&"]"&A$2:A$18&";"),"&"," "),{1,4},{3,4})),N(IF(1,ROW($2:$35)/2)),N(IF(1,MOD(ROW($2:$35),2)+1))),{1,4},,{"*&","&*"}),B$2:B$18,C2),{1;1}),))
D2
=SUM(IFERROR(1/(MMULT(COUNTIFS(A$2:A$18,REPLACE(INDEX(TRIM(MID(SUBSTITUTE(A$2:A$18,"&"," "),{1,4},{3,4})),N(IF(1,ROW($2:$35)/2)),N(IF(1,MOD(ROW($2:$35),2)+1))),{1,4},,{"*&","&*"}),B$2:B$18,C2),{1;1})*(N(OFFSET(B$1,ROW($2:$35)/2,))=C2)),))
