"Child" node skipped when optional text field left blank

The Setup

I am using the Node Widget field to allow creation of child "date" nodes, which contain the following fields:

CCK Date - "From Date" (required)
CCK Date** - "To Date" (optional)
CCK Text - "Label" (optional)

I have hidden the title field (to get around the requirement for users to enter it) and am using the Auto Title Generation module to generate the title for the child nodes automatically.

The Auto Title module is generating a title based on the one required (from) date field, so if a user leaves the date field blank, the child node title will be blank.

** SIDE NOTE: The from date is a separate field due to a bug in node widget validation that refuses to accept a blank optional "to date" when using the to/from date pairs in a single field.

The Problem

I find that child nodes are *only* saved when the user fills out the (optional) label field in addition to the required date field (the optional date field can be left blank). Why an optional text field would be the trigger for recognising the child node as "filled in" I don't know.

Thoughts?

Can someone enlighten me as to what the conditions are for not "skipping" a child node? Is this a bug? (Much about the validation and UI in this module seems a little rough around the edges). Happy to help where I can in cleaning this up?

Cheers

Daniel