When we do a squadron or group level SAREX, is it appropriate to invite other non-CAP SAR groups or jurisdictional agencies to either participate or observe?
You may want to ask this question to your Wing ES staff. There could be policies and procedures involved in regards to non-CAP entities.
As always, command chains will be consulted. The question is general enough for other squadrons to make use of the answers.
Allowed? Yes.
Appropriate? Too local to answer.
If the "A-Team" is doing simple searches and a high level of success is anticipated which
would positively demonstrate the wing's capabilities, sure.
If the "B-Team" is there doing legit first-round learning, or you have new tech involved,
or the weather might preclude much successful activity, probably not.
Local command should make the call internally, before any invites are sent externally.