Quelea - attract to a line

Hi guys,

I've made a little simulation using Quelea where agents are circulating randomly (wander force) within a certain area. I'd like to simulate a behaviour where the agents are attracted and stay close to a couple of curves -- this is where I am struggling. I can only get my agents to attract to a specific point, but not over a full length of a curve. Is this possible? If so is there anyone that knows the solution to my problem?

Print screen and file attached.

Many thanks for any help!

Christina