How does tinc determine which node to route indirect traffic through?

[rwky]

I have a network with 4 nodes., A B, C and D. They're all running 1.0.36.

A and B can be accessed directly C and D cannot. A and C are on the same LAN and can connect to each other. A and C also connect to B.

D routes traffic to C through B instead of A if it has a ConnectTo option to both B and A, if it only has a connect to to A it routes traffic through A.

Ideally I want traffic to go D -> A -> C all the time unless A is down then it should go D -> B -> C. Is there a way of getting tinc to route indirect traffic through nodes on the same lan as a priority?