to deal with ordering issues i would try a using a couple of formulas, grouping and then the select expert with a group condition
formula1 "LF_formula"
if mxu_id = 'LF' then consump else 0
formula 2 "HF_formula"
if mxu_id = 'HF' then consump else 0
group on cust_no
use the select expert in group selection as
distinctcount(mxu_id,cust_id)=2
and
maximum(@HF_formula,cust_id)>maximum(@LF_formula,cust_id)