how can I add branch to parallel activity dynamically

I have an state machine implemented using wwf which is going to handle an indent flow. Imagine that we have an indent registered by user and we want to send enquiry to different vendors. the number of enquiries are various and depends on buyer's decision that how many vendors he wants to enquire.So my state machine comes to an state named Waiting for Enquiry and I need fork here and I have different state among this fork (开发者_运维百科 I think I have to add a nested state machine) I'm adding a parallel activity but the branches of this parallel activity are depended on selected vendors as I mentioned above.when I try to add branches dynamically I receive exception because the workflow is not mach with the persisted one. is there any solution?

Sounds like you want to use the ParallelForEach instead of a Parallel with multiple branches.