Verify required fields, how to locate fields after first valitadion

how can i locate fields from a form to verify required fields?

The first field is easy, but the next one is not because in order to locate it for the next test am using coordinates and doing this coordinates are lost and can´t find the field.

Note, the form has over 30 fields, so in the mobile i have to do one or two scroll up to watch the next field that i want to verify

Example of the issue:

Verify Name as required field
1.- Miss data in the name field
2.- Capture all the rest data of the form
3-. Press save
4.- System sends error message (first test is OK)

Verify Address (i want to do this in the same script that was used in the first test)
1.- Capture data in the name field (here is the issue, how can i locate this field?, is there someway to find it?, i don´t want to clear the form and capture all again…)
2.- Miss data in the Address field (i don´t have to capture the rest of the form because its already done)
3-. Press save
4.- System sends error message (second test is OK)

Why are you using co-ordinates? Doesn’t this field have any other reliable property like id/ name or class? Can you not at least create a robust xpath for this?