Activity guide context data passing from a page to employee ID.

Hi,

We have to expose an activity guide to internet. We will have pre-authenticated link with guest user.

So as to understand who logged in, we are using a custom authentication page which will confirm zip and other details and get the employee ID.

The concern is how to pass this employee ID retrieved as context key, so that it will correctly open the activity guide for the user who gave the data correctly. even he comes back to complete the activity he/she should be pointed to his pending item.

I tried to look into Life events activity guide but that is some different piece.