bgp on two wan interfaces on the same l2

[ikonst]

Hi there,
Please refer to the diagram. I'm trying to use pfSense as a BGP peer for my NSX lab project.
I have two problems:

I can't assign IP addresses via the GUI from one network (172.18.63.0/29) on two "WAN" interfaces—I got an overlap error and had to assign them via CLI.
It seems that FRR BGP accepts BGP connections only on one interface (let's call it WAN_1 172.18.63.3/29).

My question is how to establish BGP to both pfSense interfaces?