Notifying user when a value in a parent field in a form conficts with a Summary field value.

I have a summary field that counts the number of records in a child report (grid edit) that are checked. I would like the user to be warned if there are no child records checked but in a parent field I have a value that indicates that child records should be checked. The user then has the option in edit mode to either change the parent field value or check one of the child records (in an embedded grid edit report on the form) 

The problem is that the summary field for the checked records in the child table do not calculate until the form is saved and then it is too late to notifiy the user that they have a descrepancy between the Parent value and the summary field. 

Is there a way to catch this descrepancy real time (before or as the record is being saved). I have tried having the embedded report and parent fields load at the same time but that does not catch the descrepancy.

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George Bramhall
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