https://github.com/ericmbarnard/Knockout-Validation/wiki/Native-Rules
I am using the knockout validation on my MCV3 page. The situation I have is that I have two buttons
The onlyIf option could work here:
onlyIf
FirstName: ko.observable().extend({ required: { params: true, onlyIf: function(){ return someFlagIsTrue; } }
You would need to set the someFlagIsTrue from your click event or other means.
someFlagIsTrue