"On-Demand?" Replication

I'll try to keep this short. We have a system that consists of 18 remote database servers and 1 headquarters server. All modifications to the "Vehicle" file are replicated to the headquarters server. As the saying goes, even "I" can get this part to work. Where I run into a problem is getting the updated information to the remote site when it it needed. Currently I'm trying to do a select from the headquarters server and update the local database before actually making the selection. This seems to work pretty well unless the network or database servers on the headquarters servers is down. Has anybody else had to deal with this configuration, or have any advise that I might find useful. All 18 remote sites are IWS and the Headquarters server is IDS. All Informix servers are 7.30 on NT 4.0. Thanks for any help. Shannon