Kevin gave me the solution to my problem. It's nice to know smart people. This 64 year old brain is slowing down as we speak.

At any rate the problem was mine, not his program. As you can see from the code:

..Private Sub NewLineItem()
....'Create new line item record
....Me.oItems.NewRow(New PurItemDefaults(Me.oItems.Entity.itemid))
....Me.grdItemListing.NavigateData(mmNavigate.Last)

this code isn't really needed since I was using the mmButtonSave control. Not only was the control doing a save, but there was a second save being done by me here. After commenting out these two lines, the row was added correctly and the other line items weren't affected. He said if I had used just the mmButton control this code would probably have worked correctly as well.

My only excuse is that this is from a previous implementation of my application and I must have used the mmButton in it, instead.

Thanks again, Kevin.

CU all.