Thank you for contacting us. The scenario you describe is part of several cases which our team still tries to figure out - stacking multiple dialog-like widgets together (like actionsheet + modalview, modalview and another modalview, or actionsheet and popover, for example).
As far as we have researched, iOS and the majority of the mobile applications do not feature such UI - perhaps stacking dialogs is considered too complex and avoided. I am not sure if a subsequent dialog opening should close or overlay the previously opened one - it probably varies from case to case, so I am not sure if we can implement an universally correct behavior.
My recommendation for now would be to avoid this approach, if possible.
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