This would be possible by adding custom JavaScript that does an AJAX request to get the team members. I don’t know if this can be accomplished with post object and user fields, I have not tried it using the new ACF JS API https://www.advancedcustomfields.com/resources/javascript-api/ but I do have an example of doing this with select fields here https://github.com/Hube2/acf-dynamic-ajax-select-example/tree/master/dynamic-select-example
