Subgrid add new button customisation using ribbon workbench.

Dear all,

I am facing a problem with customising a subgrid add new button .

I have a subgrid ,I want to attach a JavaScript function to the add new(+) button of the subgrid.

Reason: i have two similar subgrids with(+) on a form , say subgrid1 and subgrid2

When I click (+) button on subgrid 1 it opens the form, when it opens I want to hide say section1 and show section2

Now when I click (+) button on subgrid 2 it opens the form , when it opens I want to hide section2 and show section1.

For this i need to attach a JavaScript function to the (+) button of the subgrid. When i do the (+) button gets hidden.

Please help..

Thanks.