Alert for nodes in a group

I've been combing through thwack and there are various posts on this subject, each addressing slightly different version of Orion.

I want to create an alert for a node that is not up, for member nodes of specific groups.

For example if server1 goes down and its a member of the Node Group Exchange, then send an email

or (as a separate alert) if server2 goes down and its a member of the Node Group ERP, then send an email

This seems simple but I can't find an easy way to do it.

I have SolarWinds Orion 2015 1.2, SAM, 6.2.1, DPA 9.2. NCH 7.4, NPM 11.5.2

Thank you for any help!!

pjc