Resize movieClips according to space

Hi

I am adding MovieClips in columns and rows according to the main container with static width and height
now if user wants to enter for more rows and columns

How I should change the Moviclips size that can adjust within main container ( Blue Box as in image )

Image 1 : I am adding small white movieClips with default width and height

Image 2 : its required , small movieClips resized according to main container, when Rows and Cloumns are increased

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