Evaluation lab value 6M before a class and lab values 3-6M after class

[records333]

Scenario: 1)capture lab values and dates 6M before class 2)lab values and dates 3-6M after class. My selection criteria is coded to capture date 6M before or after class. Additionally I would like to create columns pre a1c values and post alc values. (report is grouped by patient)

I used a if formula to capture pre and post columns but records are showing null. if a patient had more than 1 lab value before or after class I would like to capture the last date and value.

 

[records333]

Selection Criteria:
(
//PRE A1C
{ORDER_RESULTS.RESULT_DATE} in [DateAdd("m", -6, {ICIC.1ST CLASS}) to {ICIC.1ST CLASS}]
)

or

(
//POST A1C
{ORDER_RESULTS.RESULT_DATE} in [DateAdd("m", 3, {ICIC.LAST CLASS}) to DateAdd("m", 6, {ICIC.LAST CLASS})]
)

What is the best way to proceed with creating formuals to make columns for Pre A1C and Post A1C without showing null values in either group? And show only the last date in either group if there were more than 1 date and value.

Example
IF{ORDER_RESULTS.RESULT_DATE}<={ICIC.1ST CLASS}

THEN {ORDER_RESULTS.RESULT_DATE}