Looping through a dynamic datagridview - .rowcount (+) changing while looping through it

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VB

DataGridView

(Windows Forms application using VB.Net)

I have a DataGridView with rows displaying the Distance and Estimated Time between two locations called the Route Leg data. I have implemented a CheckBox where if Selected it should loop through the Route Leg data and Insert the Leg Step data below the current Route Leg data.

If the CheckBox is Not Selected, a loop will remove all the Leg Step data - this part works well.

The problem is that the DataGridView's RowCount changes every time a Leg Step is added and this causes most of the lower Route Leg detail lines to be skipped.

I have tried For Each, For...Next and While loops to try and loop through the dynamically changing DataGridView. It is as if the start of the loop takes a snapshot of the number of rows (RowCount) at the start of the loop and it keeps to the original number of rows at the start of loop execution.

Here is the code I am using. It is a strip down of the actual code I wish to use:

Private Sub chkShowRouteStep_CheckedChanged(sender As Object, e As EventArgs) Handles chkShowRouteStep.CheckedChanged
        Try
            If chkShowRouteStep.Checked Then
                'Show Leg Steps
                For i As Integer = 0 To dgvQuote.RowCount - 1
                    txtRowCount.Text = i
                    If dgvQuote.Rows(i).Cells(0).Value.ToString <> "" Then
                        For j As Integer = 1 To 5
                            dgvQuote.Rows.Insert(i + j, "Step")
                        Next
                    End If
                    i += 1
                Next


            Else
                'Hide Leg Steps
                For i As Integer = dgvQuote.RowCount - 1 To 0 Step -1
                    If dgvQuote.Rows(i).Cells(0).Value.ToString = "Step" Then
                        dgvQuote.Rows.RemoveAt(i)
                    End If
                Next
            End If
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub

Is there a way where I can loop through all the lines, even those added after the loop was started?

What I have tried:

For loop
For each loop
While loop