I was working on a project, basically it's using MS InfoPath to design a form. I am currently facing an issue with the autonumbering.
Here is the scenario:
Is there a way to keep the numbering if the 2nd user updates the same form?
You could use a hidden field to check against when submitting. Set the default value to 0. Add a rule on submit where if the value of hidden field is 0, set max(ID)+1 as you're currently doing. Also, set the value of this hidden field to 1 when submitting.
Have a second rule to handle when the value of the hidden field is 1 (existing form). In this scenario, you use the same ID.