Best way to make this grid

Hi!

I'm developing a panel with several modules. Each module is represented by an "x", according to the attached image: http://imgur.com/a/1NkHu

Each module has a collider that I use to detect a touch. When I click and drag a shape into a module, the shape conforms to example 1 of the image.

My problem is that I need to make the shape grow to any direction by taking up the points touched by the user.

I have shapes modeled in all possible sizes. What I need to do, is to position them and grow them according to the module touched.

Note: Modules are not within a grid.

What is the best way to solve this?