Is it possible to add an object (eg TEXT) to a GROUP without ungrouping

Unfortunately or fortunately, you cannot add a figure to a group without ungrouping it before. For this, it is best to use a macro.
For example, if you need to add a shape (or text) to several selected groups (see the macro below).
To use the macro correctly. Select an arbitrary number of shapes, then (with Shift) select the shape (text) that you actually need to add and run the macro.
Regards.
Taras

Sub AddShapeToAllSelectedGroups()
    Dim s As Shape, s1 As Shape, s2 As Shape, SR As ShapeRange, sG As ShapeRange, gName As String

    Set SR = ActiveSelectionRange
    Set s = SR.Shapes.First

    s.RemoveFromSelection
    Set SR = ActiveSelectionRange

    For Each s1 In SR
        If s1.Type = cdrGroupShape Then
            gName = s1.Name
            Set sG = s1.UngroupEx
            Set s2 = s.Duplicate
            sG.Add s2
            Set s1 = sG.Group
            s1.Name = gName
        End If
    Next s1
    s.Delete
End Sub