I have some sort of a solution but it's quite involved ...
Try using document variables (DOCVARIABLE)
Yiu add them to a template/document, & assign a value
They'll keep this value unless they're updated
They need some VBA coding to add/update them
Use a form to update their value
Show their value in the document by using the word field {DOCVARIABLE}
example
Adding a DocVariable to a document:
ActiveDocument.Variables.Add "SurName"
Updating their value:
1. Create a form with enough text boxes to suit your purpose
2. Use this code to display their initial value in the textbox (form_load)
frmUserInput.txtSurName.Value = ActiveDocument.Variables("SurName"

.Value
3. use this code to update their value (commandbuttonOK_click)
ActiveDocument.Variables = ("SurName"

.ValuefrmUserInput.txtSurName.Value
Showing the variables' value to a document:
press <Shift-F9> & type the code DOCVARIABLE followed by the variable name between double quotes - resulting in{DOCVARIABLE "SURNAME"}
Press <F9> to update
Hope this helps
Cheers
Nikki