Forms With 2 Dimensions (looking Like A Spreadsheet)

Hello,

I'm trying to build a personnal budget application.

I need to build a form that looks like a grid.

On the first column, you will see the different budgets elements

On the top line (headers), you should see the different months of the comming year.

I already managed to build the necessary tables (with 2 keys in the table source for the form).

My questions are the following:

1) how can I build a forms that looks like a spreadsheet, proposing me every cells from the start (not only the cells that i have filled before)?

2) how can I make for this form to be dynamic ? This means that, if I add a budget element in the budget elements table, how can I make the form to be adapted automatically, adding a line under the others, for every months?

I have asked severall other forums, no one could answer me.

thanks for your help.

Stephane