BIA and Aggregates both are different performance measures... you can't combine both.
BIA : is a separate specialized server , its not part of BW server.
You won't get an option as you find "Maintain Aggregates".
Tcode: RSDDV till BW7.0 version
Tcode: RSDDB from Bw 7.30 here you can access the above tcode as well.
If you create BIA index for a particular IC , Index will be create for entire IC, there is no need to specify specifically.
In simple language BIA will execute queries with the data holding on RAM. BIA won't touch the data base while executing the queries.
Where as aggregates stores the physical data when you execute a query build on that particular info provider it touches the data base for accessing the data.
Regards
KP