How do I update information on "page 3" of HR15.1

You can do it from HR11 - you have to pass the FCr0, HRU-FIELD-TYPEr0, HRU-FIELD-KEYr0 and VALUEr0 values in.
0=zero

Unfortunately, that won't work for my situation. I am working on a New Hire flow, therefore the employee hasn't been created yet, the potential employee is still in applicant status.

Are you adding the new hire via HR11 in your flow? Or are you using a PA52.4 action? If you're using PA52.4, you should add the user field you want updated as one of the action fields. If you don't have enough fields available, you can do a 2-part action. If you're doing via HR11, then you would do the add on HR11 for the new hire, and then a change on HR11 for the user field.

If you open the form in Design Studio, you will see the syntax for field names required for Company, Employee/Applicant, etc. and you can add those values to your AGS call with the others I mentioned.

The flow uses PA31 to create the Applicant, then HR15.1 for a few user fields, then we do the PA52.4 HIRE1 action.

I did some poking on PA31, and it doesn't look like it has the pass through to HR15 like the HR11 does. If your flow does all the work and you're not going back to look at the PA31 record information, it may be easiest to just add the user fields in your PA52.4 action rather than adding them on HR15 in between.

Hi David, I know this is an old thread, but I'm also trying to update a user field that is on another page.   With the solution you are suggesting, will there be a previous HR11 inquire call or an HR15 - to know the row number?   Or is there a way to do it in one call if we know the HRU-FIELD-KEY?    Thank you!

You need to know the values ahead of time.