Maintaining tablix width when hiding some columns in rdlc report

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C#

RDLC

In our project, we got some rdl files that contains dynamic column, User can decide which to show or which to hide by a Multi-Selection Report Parameter. then it comes some problems: 1.if there is a report contains 10 columns, when the user selected 5 columns to show ,and other columns to hide, the right half page were blank. so what we need is that we can dynamically change rdlc table size by user's selection or configuration. how to resolve it ? Report's tablix have no Expression input, can it be dynamically?

thanks in advance

What I have tried:

i had tried in many ways but i cannot do that.Please help me if any one knows it.