Copy double-clicked cell to next empty row in different sheet with each double-click

I am trying to create an inventory system.

I have written code so that if you double click a product (Sheet1), it adds the relevant information about the product (columns 1,2,3, 9, 10) into the purchase order (Sheet 4).


I also have code so that it only adds a secondary product if it is from the same supplier (as seen by the value of Row 22, Column 6).

I need to find a way such that the first product double clicked is added to Row 15, Column 3 of Sheet 4. If another product is double-clicked a new row is inserted below row 15 in Sheet 4 and the relevant information is copied, etc...

Any help would be great!

This is what I have so far:

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
    'Override the default double-click behavior with this function.
    Cancel = True
    
    'Declare variables.
    Dim wks As Worksheet, xRow As Long
    
    'If an error occurs, use inline error handling.
    On Error Resume Next
    
    'Capture double-clicked cell
    Target.Select
    'Capture double-clicked row
    seRow = Target.Row
    

    seCol = 0
    'Insert in Row 15 of Sheet4
    xRow = Sheet4.Cells(Sheet4.Rows.Count, 1).End(xlUp).Row + 1
    'For first product added to purchase order
    If Sheet4.Cells(22, 6) = "" Then
        Sheet4.Cells(22, 6) = Cells(seRow, seCol + 5)
        Sheet4.Cells(xRow, 3) = Cells(seRow, seCol + 2)
        Sheet4.Cells(xRow, 9) = Cells(seRow, seCol + 6)
        Sheet4.Cells(xRow, 10) = Cells(seRow, seCol + 9)
        Sheet4.Cells(xRow, 1) = Cells(seRow, seCol + 7)
        Sheet4.Cells(xRow, 2) = Cells(seRow, seCol + 8)
        
        MsgBox "New Order Started: Producted Added to PO"
    
    'If trying to add another product to purchase order, check to make sure the vendor is the same
    Else
        If Sheet4.Cells(22, 6) = Cells(seRow, seCol + 5) Then
    
            Sheet4.Cells(xRow, 3) = Cells(seRow, seCol + 2)
            Sheet4.Cells(xRow, 9) = Cells(seRow, seCol + 6)
            Sheet4.Cells(xRow, 10) = Cells(seRow, seCol + 9)
            Sheet4.Cells(xRow, 1) = Cells(seRow, seCol + 7)
            Sheet4.Cells(xRow, 2) = Cells(seRow, seCol + 8)
    
            MsgBox "Product Added to PO"
        
        Else
            MsgBox "This item is not from the same vendor"
    End If
    End If
    
    Application.EnableEvents = True
    Application.ScreenUpdating = True
   
    End Sub