Thanks Jason - in that case I'll go with a single record insert/update for a table row, then redirect to the same page, until all the records have been entered. Must have either client and/or server validation as the fields must be entered in a fixed format that can only be achieved with a custom regex.
Alternatively could you give me an idea of how to hand-code this on this forum? I realize it's a problem with the runtime dynamic fieldname assignments. I'm quite used to adapting the code in DW server behaviors.