Merging multiple routes into a single multipath route

[Johannes Erwerle]

Hello.

I am running a setup with 2 uplinks which both have dynamic addresses 
(via DHCP) and NAT and a Linux router. So I get 2 default routes via DHCP.

I would like to use both uplinks via the linux multipath routing and I 
am searching for a way to "merge" both default routes that I get into 
one route with multiple next hops.

Is there a way to accomplish that with bird? (or any other tool?)

All of this is only relevant for IPv4.

Greetings
Jo