Missing functionality ?

[ab3263266]

Hi ,
I am trying to implement rule number SD1306 from FDA validator rules
description: When the study population is healthy subjects (TSPARMCD = 'HLTSUBJI' and TSVAL = 'Y'), the Diagnosis Group parameter should be provided with a null Parameter Value (TSVAL should be null when TSPARMCD = 'TDIGRP').
in order to do it I need to access two rows values at the same time and I didn't find the way to do it ,
I would love to know if I missed something or if the functionality is really missing

Another thing I came across is, when I want to check uniqueness between one variable and several variables at the same time, then I didn't find the way to do it. I found the way to check uniqueness only between two variables with the operator "is_not_unique_relationship". Is there a way to check it for a list of variables or only for A single variable?

Thanks in advance, Ariel