How to balance traffic on two IPSec tunnels with strongswan as a client on ubuntu?

Question

linux

ubuntu 19.04
strongswan 5.1.1 as client.
Two tunnels (policy based) IPSec with ikev2 psk
Both tunnels go up on the same client output interface (ubuntu + strongswan).
The server (where the tunnels rise) has two channels to the outside, each with a tunnel, and we connect to them.
Task:
Configure the client to increase the width of the vpn channel to the server by summing the channels of two tunnels.
The client is available for configuration, the server (Palo Alto) is under control to a limited extent.