Datagrid cell merging

[semicolon]

Hi i have a datagrid in my c# windows form and i want to merge the row
he can input data in w1, w2, w3 and .., and save.

                            weeks
Item 1 | Forecast        | w1 | w2 | w3
Item 1 | Stock on Hand   | w1 | w2 | w3
Item 1 | Orders          | w1 | w2 | w3

       | Forecast        | w1 | w2 | w3
Item 1 | Stock on Hand   | w1 | w2 | w3
       | Orders          | w1 | w2 | w3

any code or solution for this
thank you

[Momerath]

This thread shows merging cells horizontally, you'd just have to adapt it to vertical merging

[semicolon]

thank you for the respounce. solve my problem