Remote Api Question Regarding Custom Fields.

Hello,
I have been reading through all the docs I can possibly find. I’m not sure if I’m overlooking something or if what I’m attempting to do just isn’t possible.
During the create-domain Http call I am attempting to pass info into a custom field. I have tried many variations on how to do so.

Here is my call: https://awesomesite.com:10000/virtual-server/remote.cgi?program=create-domain&domain=another.awesomesite.com&pass=1234&default-features&plan=Default%20Plan&template=trueblue&VIRTUALSERVER_FIELD_ZIP=99999

VIRTUALSERVER_FIELD_ZIP is the custom field id like to pass info to during domain creation.

These are my current available variables:

VIRTUALSERVER_EDIT_RESTORE=0
VIRTUALSERVER_NAME6=1
VIRTUALSERVER_VIRT6=
VIRTUALSERVER_NETMASK=
VIRTUALSERVER_LIMIT_WEBALIZER=1
VIRTUALSERVER_EMAILTO_ADDR=vartest@awesomesite.com.com
VIRTUALSERVER_DB=vartest
DOCUMENT_REALROOT=/usr/share/webmin
VIRTUALSERVER_LOGROTATE=1
VIRTUALSERVER_MAILBOXLIMIT=
BASE_REMOTE_USER=root
VIRTUALSERVER_EDIT_SCRIPTS=0
VIRTUALSERVER_PREFIX=vartest
VIRTUALSERVER_FIELD_FINANCING=
VIRTUALSERVER_IP=xxxxxxxx
VIRTUALSERVER_EDIT_SSL=0
HTTP_CONTENT_LENGTH=538
MYSQL_PWD=xxxxxxx
VIRTUALSERVER_DB_MYSQL=vartest
VIRTUALSERVER_LIMIT_WEB=1
VIRTUALSERVER_EDIT_SPF=0
VIRTUALSERVER_ALLOWEDSCRIPTS=
VIRTUALSERVER_EDIT_DELETE=0
VIRTUALSERVER_SPAM=1
VIRTUALSERVER_EMAILTO_SRC=vartest@awesomesite.com
VIRTUALSERVER_GID=1023
USERADMIN_GROUP=vartest
VIRTUALSERVER_MAIL=1
VIRTUALSERVER_EDIT_ADMINS=0
VIRTUALSERVER_EDIT_DOMAIN=0
MINISERV_CONFIG=/etc/webmin/miniserv.conf
VIRTUALSERVER_POSTGRES=0
VIRTUALSERVER_EDIT_DNSIP=0
HTTP_USER_AGENT=Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:53.0) Gecko/20100101 Firefox/53.0
VIRTUALSERVER_OWNER=var test
VIRTUALSERVER_FIELD_LIC=
SERVER_PORT=10000
VIRTUALSERVER_EDIT_SPAM=0
VIRTUALSERVER_LIMIT_WEBMIN=0
VIRTUALSERVER_FIELD_ZIP=
GLOBAL_CITY=
VIRTUALSERVER_EDIT_FORWARD=0

Using the cli I am able to use virtualmin modify-domain --set and set my field just fine from there but is it possible to add the info during server create?
Thank you in advance.

For bit more info on my question which leads me to think I’m just doing something wrong is when I initiate this address from the browser it does what I want.

https://awsomesite.com:10000/virtual-server/domain_setup.cgi?parentuser=&to=&aliasmail=&subdom=&dom=anotherawsomesite.com&owner=another&vpass=1234&template=149505977015116&plan=0&vuser_def=1&email_def=1&mgroup_def=1&prefix_def=1&db_def=1&field_rheemorruud=1&field_propartner=1&field_reviews=&field_financing=1&field_warranty=1&field_lic=&field_streetaddress=&field_city=somewhere&field_state=&field_zip=&field_phone=&unix=1&dir=1&logrotate=1&dns=1&mail=1&web=1&webalizer=1&mysql=1&spam=1&virus=1&webmin=1&virtualmin-awstats=1&fwdto_def=1&virt=0&ip=&virt6=-2&ip6=&dns_ip_def=1&ok=Create+Server