Can special GL indicators be re-used ?

I would like to create some new special GL indicators to be used in customer deductions but our list is already quite extensive despite some of them not having GL codes assigned.

I am cautious about re-using the existing GL indicators that have no GL assigned as I know some of them are used in other programs such as the payment program F110.

Is there a way of finding out which programs use SGL indicators and is it good practice to re-name and re-use one if it is not currently used ?

Many thanks

Claire