Refreshing 1 materialized view belonging to a refresh group

Hi,

We have oracle 8i and use snapshot replication which gets refreshed every 4 hours.

We need to have one MV belonging to the refresh group to be refreshed on demand when a user does a certain operation.

Is this possible and will it create any problems later on.

We cannot refresh the whole group as it takes around 45 minutes and generates a lot of load on the system.

The MV that needs to be refreshed is a fast refreshable one.

Thanks
Ron