Linking Text Field To Hidden Field?

I have created a html purchase request form that people will fill out and submit to make purchase requests within my company. In this html form, I have a text field that is automatically populated when the page is pulled up. The text field is populated with the name of the person who is logged in and it is read only so they cannot be deceitful or anything.To get to this HTML Request form, you must log in through a webclient thus the server knows to populate your name because you are the one logged in. The text field populates because of its <input NAME = "OBProperty_CurrentUserRealName", which is a keyword the program identifies and knows to populate with the logged in users name into that particular text field.

That works all fine and dandy, so here is where the problem lies. When submitting the overall form request, the populated name isnt being saved/ carried over to the admin page so we do not know who it was submitted by.To make the persons name carry over and save, another field name keyword must be used.

Which is OBKey__163_1. Which it was suggested to me to make that the input name of a hidden field. I need "text field A" to continue to populate the form with the persons name using OBKey_CurrentUserRealName, then pass the persons name off to a hidden field containing the input name=OBKey__164_1, which will thus save/pass the persons name on with the rest of the filled out request form when its submitted.

Here is what I have:

<input name="OBProperty_CurrentUserRealName" type="text" id="buyer" style="width:100%" readonly="readonly">
<input name="OBKey__163_1" type="hidden" id="OBKey__163_1">