That was much more clear question. You’ll have to create Balancer Rules.
Here are my rules:
For the Openvpn
MARK tcp opt -- in !BRIDGE00 out * 0.0.0.0/0 -> 0.0.0.0/0 tcp spt:1194 MARK set 0x66
for the Dyndns
MARK all opt -- in BRIDGE00 out * 10.14.149.31 -> 0.0.0.0/0 MARK set 0x66
Some explanation… BRIDGE00 is my home LAN and 1194 is the Openvpn source port. Also 10.14.149.31 is the server running the Dyndns. As you can see both of them go out of the same connection (0x66).