Bird pipe/filter change on "external" conditions

[ico]

Hello,

Is there some way to change bird's configuration on some external event? 
I would use it like this:

There are 2 routers, active and passive. Active router exports default 
route for the rest of network. Passive router has exactly the same 
configuration, but filters out default route. When active/passive switch 
function, the new active somehow removes default route filter, the new 
passive adds default route filter.

Another usage would be to change interface cost in OSPF at run-time and 
thus redirecting traffic from that particular interface.

Currently I am doing it with rewritting bird's config file and reloading 
configuration. Is there some better way? Like setting some variable, 
which causes changes some filter conditions?

Thanks

ico