Load balancing based on file content

Hi All, I've done some reading but I can't seem to find a solution to what I'm trying to achieve. I would like to set up load balancing based on the receive string from a file on a server. My setup is as follows:

2 Servers in a pool, A & B

Each server has a file that needs to be queried. If the receive string is "ok" traffic is distributed based on the round robin method. If the receive string from 1 of the servers is changed load balancing is then based on priority group setting, where server A=1 and B=5.

Unlike like a health monitor, I need both servers to be able to received traffic, but distributed based on the priority group setting for the server.

Somehow this was accomplished on the A10, but I'm having a hard time trying to replicate it on the F5.

Any thoughts or suggestions on our I can achieve.

Thanks in advance for your help.

Cheers

Deena