Allow vlan to go throw STP

Hello All, 

i  need help with some configuration 

please see the picture : 

In this scenario

Link 1 between switch A and Switch B is active

Link 2 between switch A and switch D is active

Link 3 between switch A and switch C is active

The clients on the vlan 170, 180 and 191 in all switches is reachable

But STP on switch D block link 4 to switch C

And STP on switch B block link 5 to switch C

My problem:

Link 1 and 2 are overloaded

Link 3 still has capacity and i  would like to use it

What I need?

I would like the client PC5( vlan 170)  to get connection from switch A to Switch C (link 3)  and from switch C to  switch D (link 4)

That mean PC8 and PC1 still get connection via link 2. And the PC5 will get connection via link 3 then 4

I hope it is  clear  now 

Thank you in advance