You can link your person control to a list Column ( Person type ) and then use it on a Nintex Workflow action

The control is already linked to a Person or Group field. The problem is that I can't assign a Task Process to this column, because it has more than 1 element. :/

I'm trying to do the same thing you are. If I figure anything out, I'll let you know. 

Hi Roshan, I figured it out! This steps fixed my problem:

1-Go to your list settings, select the "Person or Group" column you wish to use, and change the option "Allow multiple selections" to "Yes", like this:

This should allow you to have multiple values in your Nintex Form.

2-Now on the workflow, if you wish to send an e-mail to everyone, just select the "List lookup -> Current Item -> {column with the persons}". That should work.

If you wish to assign a task to everyone, use the action "Start Task Process", and NOT the regular "Assign a task". Again, on the participants field, select  the "List lookup -> Current Item -> {column with the persons}". Now also look at the "Assignee Options menu, inside the action windows. There you can define if you wish to assign this task to everyone at the same time, or at a more serial way, in which the next person will only be assigned to the task, once the previous completed it.

I really hoe this helps you!

Regards, Igor.

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Glad you were able to figure out how to get it working! Be sure to mark your question answered so others can quickly find what you did!