SQL Fornula to check if one string or ID contains in a concat string using summary FUnctions

CASE WHEN INSTR(    TO_CHAR(REPLACE(NS_CONCAT(DISTINCT {custrecord_jj_transaction_number_ahap729.salesteammember.id}), ‘,’, ‘<br>’)),    TO_CHAR(MAX({custrecord_jj_sales_person_ahap_729.id})) ) > 0 THEN ‘Y’ ELSE ‘N’ END

add this in the formula text Maximum