I have a rather large set of data in related tables and I would like to create a survey to be used with workforce that can do the following:
pull data from existing entries if given an ID code (ideally entered in workforce).
Add new entries using input from surveys
While I know I can create surveys from existing feature services, most of the documentation I've found about previously existing data refers to overwriting entries, which is not what I want to do.
You can get Workforce to launch a Survey123 form and pass an ID to a specific field/question: Create your first project—Workforce for ArcGIS | ArcGIS
You can then use this ID as the basis a Pulldata() function. These functions are used to do an ID based lookup on a .csv, and use returned values (from various columns in the .csv) to populate the questions. This is how you can populate a survey with existing data associated. Take a look at the following: https://community.esri.com/groups/survey123/blog/2016/10/27/the-pulldata-function-access-external-da... for more information.
The only issue is that you would need to create a static.csv that contains the values you want to pre-populate. This is because you can't use pulldata() against a feature service (we do have an enhancement request open for this though and I can add you to it - if this is what you need).
Please let me know if you need any more info.