best way to consolidate data
Not sure what your problem is... the three views solution sounds best.
If consistency is your problem with that then automate the creation of the views.
Use a function to return the common "logic"

Create function fn_GetStaticViewElement()
   return CONVERT(VARCHAR(MAX),',SUM(CASE WHEN IncludeColumn = 1 AND SecondInclude IN(5) THEN 1 ELSE 0 END) as Column1,SUM(CASE WHEN IncludeColumn = 1 AND SecondInclude IN(6) THEN 1 ELSE 0 END) as Column2,SUM(CASE WHEN IncludeColumn = 1 AND SecondInclude IN(4) THEN 1 ELSE 0 END) as Column3')

Create proc proc_GenerateViews

'ALTER VIEW vwALL
execSQL ('ALTER VIEW vwALL AS Select ... ' + fnGetStaticViewElement() + '...From...Where...')
'ALTER VIEW Board
execSQL ('ALTER VIEW vwBoard AS Select ... ' + fnGetStaticViewElement() + '...From... Where...')
'ALTER VIEW School
execSQL ('ALTER VIEW vwSchool AS Select ... ' + fnGetStaticViewElement() + '...From... Where...')


to have the data combined:
Create 1 huge view, union all the sources, combining all the possible columns.
De-normalised.
Expose sourcename into a column.
use that as part of your filter.
Should act like a partitioned view, I think.