I'd like to know whether the conditional clause "should they occur" requires an auxiliary like "will" in the main clause of the following:
In general, governments [will?] act to prevent the formation of gangs or break them up should they occur.
I'd appreciate your help.
Since you begin the sentence with In general and are talking about standard operating procedure / normal practice, there's really no need for should; you could say when they occur.
Your sentence is running at cross purposes with itself by mixing the general with the conditional. When dealing with "standard operating procedure" or "normal practice", the farther we get from simple when the more marginal the sentence gets:
Governments will break gangs up when |if they form.
Governments break gangs up when | if they form.
Governments break gangs up should they form.
Governments break gangs up were they to form.
Adding will to those last two statements doesn't rescue them:
Governments will break gangs up should they form.
Governments will break gangs up were they to form.
Or
The Streets Department repairs potholes when they are reported.
The Streets Department repairs potholes if they are reported.
The Streets Department repairs potholes should they be reported.
The Streets Department repairs potholes were they to be reported.
Or
The answering services handles calls when they come in after hours.
The answering services handles calls if they come in after hours.
The answering services handles calls should they come in after hours.
The answering services handles calls were they to come in after hours.
You are correct, the sentence In general, governments [will?] act to prevent the formation of gangs or break them up should they occur. is invalid without an auxiliary. However, in the context of In general, governments [will?] act to prevent the formation of gangs or break them up., the sentence is valid whether or not the auxiliary is there or not
