pppd retry issue with multiple wan interfaces

Question

I am using two wan connections in my router with linux kernel 2.6.21. PPPOE Ethernet cable and 3G connection. Both need ppp setup. But boot sequence is different for both. many times 3G disconnect and need to reconnect or sometime pppoe disconnect and need to reconnect.

To give retry on 3G or PPPOE I need to do $killall pppd and because of that other connection of pppoe or 3G gets disconnected.

Is there any other way than $killall pppd while retrying the connection for 3G or pppoe ?

Thanks in advance.