Restricted editing in Word Fillable form

Techsolver Assuming that you are using a version of Office that supports the use of Content Controls, if you select the row that you want to repeat and then insert a Repeating Section Content Control

For more on the use of Content Controls, see the following and other pages of Greg Maxey's website:

https://gregmaxey.com/word_tip_pages/content_controls.html

If for some reason you do not want to use Content Controls, you could have a macro, similar to the following, set to be run on exit from the last formfield in the row that you want to be repeated.  Note, the macro will need to be modified to suit the FormFields that you are using in that row.

Sub Addrow()
Dim rownum As Integer, i As Integer
With ActiveDocument
    .Unprotect
    .Tables(1).Rows.Add
    rownum = .Tables(1).Rows.Count
    For i = 1 To 3
        .FormFields.Add Range:=.Tables(1).Cell(rownum, i).Range, 
Type:=wdFieldFormTextInput
    Next i
    .FormFields.Add Range:=.Tables(1).Cell(rownum, 4).Range, 
Type:=wdFieldFormDropDown
    With .Tables(1).Cell(rownum, 4).Range.FormFields(1).DropDown.ListEntries
        .Add "Item1"
        .Add "Item2"
        .Add "Item3"
        .Add "Item4"
        .Add "Item5"
    End With
    .FormFields.Add Range:=.Tables(1).Cell(rownum, 5).Range, 
Type:=wdFieldFormDropDown
    With .Tables(1).Cell(rownum, 5).Range.FormFields(1).DropDown.ListEntries
        .Add "ItemA"
        .Add "ItemB"
        .Add "ItemC"
        .Add "ItemD"
        .Add "ItemE"
    End With
    .Tables(1).Cell(rownum, 5).Range.FormFields(1).ExitMacro = "addrow"
    .Tables(1).Cell(rownum, 1).Range.FormFields(1).Select
    .Protect Type:=wdAllowOnlyFormFields, NoReset:=True
End With