Possibility to set acct_table1 outside of sql.conf?

Dear All, i would like to insert Accounting-Information in different tables for different NASs. Therefor i would use different sql-Instances and the acct_users file. The instances would only differ in acct_tabl1 and acct_table2. I tryed to set the variables in the sections of every instance in radiusd.conf before including sql.conf. In sql.conf i commented out the variables. But then there is reported an error, that the variable acct_table1 is unknown. Is there a possibility to set the variables acct_table1 and acct_table2 in the sections for the different instances in radiusd.conf? Or have i to provide for every instance an own sql.conf. Hopefully my problem gets clear!? Thank you Andreas Engler