transfer field data from stateless form

transfer field data from stateless form

I have two stateful forms - "Entry Form" and "Entry Detail Form" and have set up the Entry Form with Entry Details Form as a sub-form.  Unfortunately the scripted calculations carried out in the sub-form, whilst they work in stand alone form, do not work in sub-form, so I thought I would try to make entries to the sub-form using a stateless form "Class Entry".
However although I have set up the stateless form and it works perfectly properly, and despite reading and re-reading the advice in Developer Guide, I cannot understand how to transfer data entered in the stateless form to the stateful form.
Could you please tell me what is the code for transferring the following fields "Rider", "Horse", "C1", "C2" etc to "C6" and "Fees" in the stateless form to fields with the same names in the stateful form.  Or should I change the field names and then transfer, and if so how do I make the transfer?
Many thanks
David