Ok, this is more of a SQL question than a Crystal question. However, be sure you read my blog to understand why you should NOT be joining multiple commands. http://scn.sap.com/community/crystal-reports/blog/2015/04/01/best-practices-when-using-commands-with-crystal-reports.
Now, here's the logic you'll need to follow to get what you need:
Select <all of the fields for the report>
from <CRM table> as crm
<joins to other tables>
inner join (
select CustomerAccountField, max(CRM.CRMRecordID)
from CRMTable
where <various criteria as needed> <-- Optional
group by CustomerAccountField
) as maxRec
on crm.CRMRecordID = maxRec.CRMRecordID
where <filter criteria>
-Dell