We are establishing the parent child work centers for finite scheduling purposes.  However, a machine can only be allocated to one parent.  We need to be able to allocate to more than one parent.  
 
For example let's use machines A, B, & C and item numbers 10, 20, & 30.
 
Here is the scenarios we have:  item 10 can run on A or B;  item 20 can run on B or C; and item 30 can run on A, B, or C.  When I set up machine B as a child, I can only select one parent.  
 
How can we get around this limitation?