SQL Server SSIS change variable

I have a package that loads 300 tables from DB2 to SQL Server.  We added a column to all the DB2 tables to keep track of changes named DW_LASTTIME.  
My question is, each table has a data flow task with the source table having a variable like this to pull the data.

"SELECT * FROM ABC WHERE LASTTIME >= " +  @[User::strAdjLastRunTime] +" WITH ur"

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So I need to update all 300 to make it say

"SELECT * FROM ABC WHERE DW_LASTTIME >= " +  @[User::strAdjLastRunTime] +" WITH ur"

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Is there any way to do this without having to manually open and update each dataflow?  Like in a text editor or something?  I know SSIS packages are just XML files but I was told if you mess with the actually file, it can corrupt it.

Thanks!

Jim