I assume you mean
With the table.RemoveRow() function you can specify which row to remove, but with the table.AddRow() function you cannot specify on which row the the AddRow works. It would be really nice to be able to specify where to add the row, but alas, AddRow will only add a row to the end of the table.
Maybe it can be incorperated in future development?
I have recently by-passed this problem in my own code.
I allow the user to build a play-list for a simple MP3 player. Usually a new item would go on the end, but the user might want to promote it to earlier in the sequence. So I added a numeric sort column to the table (which could be invisible). Then to move a column up or down the value of the sort cell is exchanged with the one above or below it (respectively).
This is more complicated to program, but offers more flexibility.