Hi,

Try

Define names


LastRow =MATCH("zzzzzzzzz",Sheet1!$M:$M)
PartsNo =Sheet1!$M$2:INDEX(Sheet1!$M:$M,LastRow)
Qty =Sheet1!$N$2:INDEX(Sheet1!$N:$N,LastRow)
WIP_No =Sheet1!$O$2:INDEX(Sheet1!$O:$O,LastRow)


In T3 and copied down,

=IFERROR(INDEX(WIP_No,MATCH(TRUE,INDEX(PartsNo&"|" &Qty=R3&"|"&S3,0,0),0)),"Not found")