Hello - I've been using Nintex for O365 for a few months. I have an interesting scenario but I am not sure if its possible.

Scenario: 

I want to create a from with 2 distinct groups with various fields (i.e. line of text, dropdowns etc...) We want to give access to both internal and external users to the form. But we want to hide or limit external users from seeing what is in the grouping for internal users, and vice versa. Ideally I'm trying to find some sort of solution where users can view aspects of 1 form but limit what they can see based on if they are internal or external users. 

I did some research and saw that we can use "isMemberofGroup" based on groups that can be created for a SharePoint list. But I have no idea how to use it... I have an internal group and external group created in SharePoint. I've worked with the creating some basic rules for the fields within the form but nothing like this before. 

Would appreciate any help or suggestions you might have. 

Thank you