Open form to ID and add in the record if not there

[Velo]

Hello, I have an issue opening a form to an ID of the record I am currently
on. If I am on frmProjects and am adding a typing in a new EndUser from the
dropdown in cboEndUser I want to be able to do two things:
1) Add this new EndUser name in the frmEndUserDetails in control source
EndUserID (named cboEndUser) once I tab out of it
2) Have this new EndUser nae appear in the frmProjects once I finish adding
details about this new End User in frmEndUser.

So what happpens is that if I need to enter a new EndUser name in
cboEndUser, once i tab out of cboEndUser the frmEndUserDetails opens to that
new EndUser I just entered and is based on EndUserID.

My EndUserID on tblProjects is a combobox with row source query
SELECT tblEndUser.[EndUserID], [tblEndUser].[End User] FROM tblEndUser ORDER
BY [tblEndUser].[End User];

It is kinda like add new record if not there and if it is there then go to
it. If it is there then I just double click the field cboEndUserID and it
does go to the frmEndUser based on that id so I am good if it already exists.
Problem is getting it added if not exists.

thank you...