HI!
You have created 3 top level VIs, right? And now you would like to run they toghether in a FiledPoint, if I understood correctly.
It is possible, except if they access different resources, I suppose. For example, it is not optimal that 2 VI access the same COM port (this is what you'd like to do, isn't it?). Maybe, that's why they don't work together.
I think you should re-engineer your code to separate task into different VI: for example, you program to have only one subVI that open COM port, and the other subVIs, which formerly communicated directly to PC, send someway data to this subVI, and this subVI handle messages....
What kinfd of FieldPoint module are you using? This can help..... Iak file should not matter, upon what you stated.
have a nice day!
graziano