HELP!!!
 
I can't figure out how to do this.  Here's the senario.
 
We have part that has four processes to it.  One of the proccesses takes a while so we would like to farm it out when we are busy but not all the time.
 
I have the raw material, of type R with a route built as follows to a type A part:
 
10 - saw to length
20 - lathe to spec
25 - outside process lathe - type A
30 - mill
40 - heat treat
 
step 25 is an alternate step to replace step 20 when we don't have the bandwidth to do this step.  How do I do a PO for this alternate step?  I have tried a service PO but that wants a seq with type P.  If it's a type P, it's assumed  the outside process happens every time, which is not the case.  
 
If I do a purchase PO, it receives the unfinished part before the other steps are complete causing an even greater problem.
 
Any suggestions or ideas would be a great help,
 
Tim